BubbleWrap for RubyMotion

A collection of (tested) helpers and wrappers used to wrap Cocoa Touch and AppKit code and provide more Ruby like APIs.

BubbleWrap website BubbleWrap mailing list

Installation

gem install bubble-wrap

Setup

1. Edit the Rakefile of your RubyMotion project and add the following require line:

require 'bubble-wrap'

If you using Bundler:

gem "bubble-wrap", "~> 1.7.1"

BubbleWrap is split into multiple modules so that you can easily choose which parts are included at compile-time.

The above example requires the core and http modules. If you wish to only include the core modules use the following line of code instead:

require 'bubble-wrap/core'

If you wish to only include the HTTP wrapper:

require 'bubble-wrap/http'

If you wish to only include the RSS Parser wrapper:

require 'bubble-wrap/rss_parser'

If you wish to only include the Reactor wrapper:

require 'bubble-wrap/reactor'

If you wish to only include the UI-related wrappers:

require 'bubble-wrap/ui'

If you wish to only include the Camera wrapper:

require 'bubble-wrap/camera'

If you wish to only include the Location wrapper:

require 'bubble-wrap/location'

If you wish to only include the Media wrapper:

require 'bubble-wrap/media'

If you wish to only include the Mail wrapper:

require 'bubble-wrap/mail'

If you wish to only include the SMS wrapper:

require 'bubble-wrap/sms'

If you wish to only include the NetworkIndicator wrapper:

require 'bubble-wrap/network-indicator'

If you want to include everything (ie kitchen sink mode) you can save time and do:

require 'bubble-wrap/all'

Note: DON'T use app.files = in your Rakefile to set up your files once you've required BubbleWrap. Make sure to append onto the array or use +=.

2. Now, you can use BubbleWrap extension in your app:

class AppDelegate
  def application(application, didFinishLaunchingWithOptions:launchOptions)
    puts "#{App.name} (#{App.documents_path})"
    true
  end
end

Note: You can also vendor this repository but the recommended way is to use the versioned gem.

Core

Misc

UUID generator:

BubbleWrap.create_uuid
=> "68ED21DB-82E5-4A56-ABEB-73650C0DB701"

Localization (using NSBundle.mainBundle.localizedStringForKey):

BubbleWrap.localized_string(:foo, 'fallback')
=> "fallback"

Color conversion:

BubbleWrap.rgba_color(23, 45, 12, 0.4)
=> #<UIDeviceRGBColor:0x6db6ed0>
BubbleWrap.rgb_color(23, 45, 12)
=> #<UIDeviceRGBColor:0x8ca88b0>
'blue'.to_color
=> #<UICachedDeviceRGBColor:0xda535c0>
'dark_gray'.to_color
=> #<UICachedDeviceWhiteColor:0x8bb5be0>
'#FF8A19'.to_color
=> #<UIDeviceRGBColor:0x8d54110>
'#88FF8A19'.to_color # ARGB format
=> #<UIDeviceRGBColor:0xca0fe00>

Debug flag:

BubbleWrap.debug?
=> false
BubbleWrap.debug = true
=> true
BubbleWrap.debug?
=> true

App

A module with useful methods related to the running application

> App.documents_path
# "/Users/mattetti/Library/Application Support/iPhone Simulator/5.0/Applications/EEC6454E-1816-451E-BB9A-EE18222E1A8F/Documents"
> App.resources_path
# "/Users/mattetti/Library/Application Support/iPhone Simulator/5.0/Applications/EEC6454E-1816-451E-BB9A-EE18222E1A8F/testSuite_spec.app"
> App.name
# "testSuite"
> App.identifier
# "io.bubblewrap.testSuite"
> App.alert("BubbleWrap is awesome!")
# creates and shows an alert message.
> App.alert("BubbleWrap is awesome!", {cancel_button_title: "I know it is!", message: "Like, seriously awesome."})
# creates and shows an alert message with optional parameters.
> App.run_after(0.5) {  p "It's #{Time.now}"   }
# Runs the block after 0.5 seconds.
> App.open_url("http://matt.aimonetti.net")
> App.open_url("tel://123456789")
# Opens the url using the device's browser. Can also open custom URL schemas (accepts a string url or an instance of `NSURL`.)
> App.can_open_url("tel://")
# Returns whether the app can open a given URL resource.
> App::Persistence['channels'] # application specific persistence storage
# ['NBC', 'ABC', 'Fox', 'CBS', 'PBS']
> App::Persistence['channels'] = ['TF1', 'France 2', 'France 3']
# ['TF1', 'France 2', 'France 3']
> App.environment
# 'test'

Other available methods:

• App.notification_center
• App.user_cache
• App.states
• App.frame
• App.delegate
• App.shared
• App.window
• App.current_locale
• App.release?
• App.test?
• App.development?

Device

A collection of useful methods about the current device:

Examples:

> Device.iphone?
# true
> Device.ipad?
# false
> Device.camera.front?
# true
> Device.camera.rear?
# true
> Device.orientation
# :portrait
> Device.interface_orientation
# :portrait
> Device.simulator?
# true
> Device.ios_version
# "6.0"
> Device.retina?
# false
> Device.screen.width
# 320
> Device.screen.height
# 480
> Device.screen.width_for_orientation(:landscape_left)
# 480
> Device.screen.height_for_orientation(:landscape_left)
# 320
> Device.vendor_identifier
# <NSUUID>

Camera

Added interface for better camera access:

# Uses the front camera
BW::Device.camera.front.picture(media_types: [:movie, :image]) do |result|
  image_view = UIImageView.alloc.initWithImage(result[:original_image])
end

# Uses the rear camera
BW::Device.camera.rear.picture(media_types: [:movie, :image]) do |result|
  image_view = UIImageView.alloc.initWithImage(result[:original_image])
end

# Uses the photo library
BW::Device.camera.any.picture(media_types: [:movie, :image]) do |result|
  image_view = UIImageView.alloc.initWithImage(result[:original_image])
end

# Lets the user edit the photo (with access to the edited and original photos)
BW::Device.camera.any.picture(allows_editing: true, media_types: [:image]) do |result|
  edited_image_view = UIImageView.alloc.initWithImage(result[:edited_image])
  original_image_view = UIImageView.alloc.initWithImage(result[:original_image])
end

Options include:

• :allows_editing - Boolean; whether a user can edit the photo/video before picking
• :animated - Boolean; whether to display the camera with an animation (default true)
• :on_dismiss - Lambda; called instead of the default dismissal logic
• :media_types - Array; containing any of [:movie, :image]

JSON

BW::JSON wraps NSJSONSerialization available in iOS5 and offers the same API as Ruby's JSON std lib. For apps building for iOS4, we suggest a different JSON alternative, like AnyJSON.

BW::JSON.generate({'foo' => 1, 'bar' => [1,2,3], 'baz' => 'awesome'})
=> "{\"foo\":1,\"bar\":[1,2,3],\"baz\":\"awesome\"}"
BW::JSON.parse "{\"foo\":1,\"bar\":[1,2,3],\"baz\":\"awesome\"}"
=> {"foo"=>1, "bar"=>[1, 2, 3], "baz"=>"awesome"}

NSIndexPath

Helper methods added to give NSIndexPath a bit more of a Ruby interface.

NSNotificationCenter

Helper methods to give NSNotificationCenter a Ruby-like interface:

def viewWillAppear(animated)
  @foreground_observer = App.notification_center.observe UIApplicationWillEnterForegroundNotification do |notification|
    loadAndRefresh
  end

  @reload_observer = App.notification_center.observe 'ReloadNotification' do |notification|
    loadAndRefresh
  end
end

def viewWillDisappear(animated)
  App.notification_center.unobserve @foreground_observer
  App.notification_center.unobserve @reload_observer
end

def reload
  App.notification_center.post 'ReloadNotification'
end

NSUserDefaults

Helper methods added to the class repsonsible for user preferences used by the App::Persistence module shown below.

Persistence

Offers a way to persist application specific information using a very simple interface:

> App::Persistence['channels'] # application specific persistence storage
# ['NBC', 'ABC', 'Fox', 'CBS', 'PBS']
> App::Persistence['channels'] = ['TF1', 'France 2', 'France 3']
# ['TF1', 'France 2', 'France 3']
> App::Persistence.delete('channels')
# ['TF1', 'France 2', 'France 3']
> App::Persistence['something__new'] # something previously never stored
# nil
> App::Persistence.all
# {'all':'values', 'stored':'by', 'bubblewrap':'as a hash!'}

Observers

Since: > version 0.4

You can observe for object's changes and trigger blocks:

class ExampleViewController < UIViewController
  include BW::KVO

  def viewDidLoad
    @label = UILabel.alloc.initWithFrame [[20,20],[280,44]]
    @label.text = ""
    view.addSubview @label

    observe(@label, :text) do |old_value, new_value|
      puts "Hello from viewDidLoad!"
    end
  end

  def viewDidAppear(animated)
    observe(@label, :text) do |old_value, new_value|
      puts "Hello from viewDidAppear!"
    end
  end

end

String

The Ruby String class was extended to add #camelize and #underscore methods.

> "matt_aimonetti".camelize
=> "MattAimonetti"
> "MattAimonetti".underscore
=> "matt_aimonetti"

Time

The Time Ruby class was added a class level method to convert a iso8601 formatted string into a Time instance.

> Time.iso8601("2012-05-31T19:41:33Z")
=> 2012-05-31 21:41:33 +0200

Location

Interface for Ruby-like GPS and compass access (the CoreLocation framework):

> BW::Location.enabled? # Whether location services are enabled on the device
=> true
> BW::Location.authorized? # If your app is authorized to use location services
=> false

BW::Location.get(purpose: 'We need to use your GPS because...') do |result|
  p "From Lat #{result[:from].latitude}, Long #{result[:from].longitude}"
  p "To Lat #{result[:to].latitude}, Long #{result[:to].longitude}"
end

BW::Location.get_compass do |result|
  p result[:magnetic_heading] # Heading towards magnetic north
  p result[:true_heading] # Heading towards true north
  p result[:accuracy] # Potential error between magnetic and true heading
  p result[:timestamp] # Timestamp of the heading calculation
end

BW::Location.get_significant is also available, for monitoring significant location changes.

BW::Location also supports get_once-style methods, which will return the first result before ending the search:

BW::Location.get_once(desired_accuracy: :three_kilometers, ...) do |result|
  if result.is_a?(CLLocation)
    p result.coordinate.latitude
    p result.coordinate.longitude
  else
    p "ERROR: #{result[:error]}"
  end
end

BW::Location.get_compass_once do |heading|
  p result[:magnetic_heading]
  p result[:true_heading]
  p result[:accuracy]
  p result[:timestamp]
end

iOS 8 Location Requirements

iOS 8 introduced stricter location services requirements. Although BubbleWrap will handle most of this for you automatically, you are required to add a few key/value pairs to the Info.plist. Add these two lines to your Rakefile (with your descriptions, obviously):

app.info_plist['NSLocationAlwaysUsageDescription'] = 'Description'
app.info_plist['NSLocationWhenInUseUsageDescription'] = 'Description'

Note: you need both keys to use get_once, so it's probably best to just include both no matter what. See Apple's documentation on iOS 8 location services requirements for more information.

Motion

Interface for the accelerometer, gyroscope, and magnetometer sensors (the CoreMotion framework). You can access each sensor individually, or you can get data from all of them at once using the BW::Motion.device interface, which delegates to CMMotionManager#deviceMotion.

Each sensor has an every and once method. every expects a time interval, and you will need to retain the object it returns and call #stop on it when you are done with the data.

The every and once methods can accept a :queue option. The default value is a queue that runs on the main loop, so that UI updates can be processed in the block. This is useful, but not recommended by Apple, since the events can come in at a high rate. If you want to use a background queue, you can either specify an NSOperationQueue object, or you can use one of these symbols:

• :main - NSOperationQueue.mainQueue, this is the default value.
• :background - BubbleWrap will create a new NSOperationQueue.
• :current - BubbleWrap will use NSOperationQueue.currentQueue.

If you pass a string instead, a new queue will be created and its name property will be set to that string.

The CMDeviceMotion interface (BW::Motion.device) accepts a :reference option, which specifies the CMAttitudeReferenceFrame. The default value is the same as the one that CMMotionManager uses, which is returned by the CMMotionManager#attitudeReferenceFrame method. This option should be passed to the repeat, every or once methods.

Accelerometer

BW::Motion.accelerometer.available?
BW::Motion.accelerometer.data  # returns CMAccelerometerData object or nil

# ask the CMMotionManager to update every 5 seconds
BW::Motion.accelerometer.every(5) do |result|
  # result contains the following data (from CMAccelerometerData#acceleration):
  p result[:data]  # the CMAccelerometerData object
  p result[:acceleration]  # the CMAcceleration struct
  p result[:x]  # acceleration in the x direction
  p result[:y]  #          "          y direction
  p result[:z]  #          "          z direction
end

# every, start, and repeat all need to be stopped later.
BW::Motion.accelerometer.stop

# repeat, but don't set the interval
BW::Motion.accelerometer.repeat do |result|
end

# you can specify a :queue where the operations will be executed.  See above for details
BW::Motion.accelerometer.every(5, queue: :background) { |result| ... }
BW::Motion.accelerometer.every(5, queue: :main) { |result| ... }
BW::Motion.accelerometer.every(5, queue: :current) { |result| ... }
BW::Motion.accelerometer.every(5, queue: 'my queue') { |result| ... }

BW::Motion.accelerometer.once do |result|
  # ...
end

Gyroscope

BW::Motion.gyroscope.available?
BW::Motion.gyroscope.data  # returns CMGyroData object or nil

# ask the CMMotionManager to update every second.
BW::Motion.gyroscope.every(1) do |result|
  # result contains the following data (from CMGyroData#rotationRate):
  p result[:data]  # the CMGyroData object
  p result[:rotation]  # the CMRotationRate struct
  p result[:x]  # rotation in the x direction
  p result[:y]  #        "        y direction
  p result[:z]  #        "        z direction
end
BW::Motion.gyroscope.stop

BW::Motion.gyroscope.once do |result|
  # ...
end

Magnetometer

BW::Motion.magnetometer.available?
BW::Motion.magnetometer.data  # returns CMMagnetometerData object or nil

# ask the CMMotionManager to update every second
BW::Motion.magnetometer.every(1) do |result|
  # result contains the following data (from CMMagnetometerData#magneticField):
  p result[:data]  # the CMMagnetometerData object
  p result[:field]  # the CMMagneticField struct
  p result[:x]  # magnetic field in the x direction
  p result[:y]  #           "           y direction
  p result[:z]  #           "           z direction
end
BW::Motion.magnetometer.stop

BW::Motion.magnetometer.once do |result|
  # ...
end

Device Motion

This is an amalgam of all the motion sensor data.

BW::Motion.device.available?
BW::Motion.device.data  # returns CMDeviceMotion object or nil

BW::Motion.device.every(1) do |result|
  # result contains the following data:
  p result[:data]  # the CMDeviceMotion object
  # orientation data, from CMDeviceMotion#attitude
  p result[:attitude]  # the CMAttitude struct
  p result[:roll]
  p result[:pitch]
  p result[:yaw]
  # rotation data, from CMDeviceMotion#rotationRate
  p result[:rotation]  # the CMRotationRate struct
  p result[:rotation_x]
  p result[:rotation_y]
  p result[:rotation_z]
  # gravity+acceleration vector, from CMDeviceMotion#gravity
  p result[:gravity]  # the CMAcceleration struct
  p result[:gravity_x]
  p result[:gravity_y]
  p result[:gravity_z]
  # just the acceleration vector, from CMDeviceMotion#userAcceleration
  p result[:acceleration]  # the CMAcceleration struct
  p result[:acceleration_x]
  p result[:acceleration_y]
  p result[:acceleration_z]
  # the magnetic data, from CMDeviceMotion#magneticField
  p result[:magnetic]  # the CMCalibratedMagneticField struct
  p result[:magnetic_field]  # the CMMagneticField struct from the CMCalibratedMagneticField
  p result[:magnetic_x]
  p result[:magnetic_y]
  p result[:magnetic_z]
  p result[:magnetic_accuracy]  # this will be a symbol, :low, :medium, :high, or nil if the magnetic data is uncalibrated

  # less useful data from CMAttitude, unless you're into the whole linear algebra thing:
  p result[:matrix]  # CMAttitude#rotationMatrix
  p result[:quarternion]  # CMAttitude#quarternion
end

# the reference frame should be one of the CMAttitudeReferenceFrame constants...
ref = CMAttitudeReferenceFrameXArbitraryZVertical
# ... or one of these symbols: :arbitrary_z, :corrected_z, :magnetic_north, :true_north
ref = :corrected_z
BW::Motion.device.every(1, queue: :background, reference: ref) { |result| ... }

BW::Motion.device.once do |result|
  # ...
end

Media

Added wrapper for playing remote and local media. Available are modal and custom presentation styles:

# Plays in your custom frame
local_file = NSURL.fileURLWithPath(File.join(NSBundle.mainBundle.resourcePath, 'test.mp3'))
BW::Media.play(local_file) do |media_player|
  media_player.view.frame = [[10, 100], [100, 100]]
  self.view.addSubview media_player.view
end

# Plays in an independent modal controller
BW::Media.play_modal("http://www.hrupin.com/wp-content/uploads/mp3/testsong_20_sec.mp3")

Mail

Wrapper for showing an in-app mail composer view.

# Opens as a modal in the current UIViewController
BW::Mail.compose(
  delegate: self, # optional, defaults to rootViewController
  to: [ "[email protected]" ],
  cc: [ "[email protected]", "[email protected]" ],
  bcc: [ "[email protected]" ],
  html: false,
  subject: "My Subject",
  message: "This is my message. It isn't very long.",
  animated: false
) do |result, error|
  result.sent?      # => boolean
  result.canceled?  # => boolean
  result.saved?     # => boolean
  result.failed?    # => boolean
  error             # => NSError
end

SMS

Wrapper for showing an in-app message (SMS) composer view.

# Opens as a modal in the current UIViewController
    BW::SMS.compose (
    {
       delegate: self, # optional, will use root view controller by default
       to: [ "1(234)567-8910" ],
       message: "This is my message. It isn't very long.",
       animated: false
    }) {|result, error|
       result.sent?      # => boolean
       result.canceled?  # => boolean
       result.failed?    # => boolean
       error             # => NSError
      }

NetworkIndicator

Wrapper for showing and hiding the network indicator (the status bar spinner).

    BW::NetworkIndicator.show  # starts the spinner
    BW::NetworkIndicator.hide  # stops it

    # the nice thing is if you call 'show' multiple times, the 'hide' method will
    # not have any effect until you've called it the same number of times.
    BW::NetworkIndicator.show
    # ...somewhere else
    BW::NetworkIndicator.show

    # ...down the line
    BW::NetworkIndicator.hide
    # indicator is still visible

    BW::NetworkIndicator.hide
    # NOW the indicator is hidden!

    # If you *really* want to hide the indicator immediately, you can call `reset!`
    # but this is in no way encouraged.
    BW::NetworkIndicator.reset!

    # and for completeness, a check to see if the indicator is visible
    BW::NetworkIndicator.visible?

UI

Gestures

Extra methods on UIView for working with gesture recognizers. A gesture recognizer can be added using a normal Ruby block, like so:

    view.when_tapped do
      UIView.animateWithDuration(1,
        animations:lambda {
          # animate
          # @view.transform = ...
        })
    end

There are similar methods for pinched, rotated, swiped, panned, and pressed (for long presses). All of the methods return the actual recognizer object, so it is possible to set the delegate if more fine-grained control is needed.

In order to prevent retain cycles due to strong references within the passed block, use the use_weak_callbacks flag so the blocks do not retain a strong reference to self:

BubbleWrap.use_weak_callbacks = true

UIViewController

A custom method was added to UIViewController to return the content frame of a view controller.

UIControl / UIButton

Helper methods to give UIButton a Ruby-like interface. Ex:

button.when(UIControlEventTouchUpInside) do
  self.view.backgroundColor = UIColor.redColor
end

Set the use_weak_callbacks flag so the blocks do not retain a strong reference to self:

BubbleWrap.use_weak_callbacks = true

UIBarButtonItem

BW::UIBarButtonItem is a subclass of UIBarButtonItem with an natural Ruby syntax.

Constructors

Instead specifying a target-action pair, each constructor method accepts an optional block. When the button is tapped, the block is executed.

BW::UIBarButtonItem.system(:save) do
  # ...
end

title = "Friends"
BW::UIBarButtonItem.styled(:plain, title) do
  # ...
end

image = UIImage.alloc.init
BW::UIBarButtonItem.styled(:bordered, image) do
  # ...
end

image     = UIImage.alloc.init
landscape = UIImage.alloc.init
BW::UIBarButtonItem.styled(:bordered, image, landscape) do
  # ...
end

view = UIView.alloc.init
BW::UIBarButtonItem.custom(view) do
  # ...
end
# NOTE: The block is attached to the view as a single tap gesture recognizer.

The .new constructor provides a flexible, builder-style syntax.

options = { :system => :save }
BW::UIBarButtonItem.new(options) do
  # ...
end

options = { :styled => :plain, :title => "Friends" }
BW::UIBarButtonItem.new(options) do
  # ...
end

options = { :styled => :bordered, :image => UIImage.alloc.init }
BW::UIBarButtonItem.new(options) do
  # ...
end

options = {
  :styled    => :bordered,
  :image     => UIImage.alloc.init,
  :landscape => UIImage.alloc.init
}
BW::UIBarButtonItem.new(options) do
  # ...
end

options = { :custom => UIView.alloc.init }
BW::UIBarButtonItem.new(options) do
  # ...
end
# NOTE: The block is attached to the view as a single tap gesture recognizer.

Button types

The .styled button types are:

:plain
:bordered
:done

And the .system button types are:

:done
:cancel
:edit
:save
:add
:flexible_space
:fixed_space
:compose
:reply
:action
:organize
:bookmarks
:search
:refresh
:stop
:camera
:trash
:play
:pause
:rewind
:fast_forward
:undo
:redo
:page_curl

UIActivityViewController

BW::UIActivityViewController is a subclass of UIActivityViewController with an natural Ruby syntax.

You can initiate a UIActivityViewController with or without a completion handler block. For more information on UIActivityViewControllers, see Apple's documentation.

# Without a completion handler
BW::UIActivityViewController.new(
  items: "Some Text", # or ["Some Text", NSURL.URLWithString('http://www.rubymotion.com')] or a UIImage
  animated: true, # Defaults to true
  excluded: :add_to_reading_list # One item or an array
)

# With completion handler
BW::UIActivityViewController.new(
  items: "Some Text",
  animated: true,
  excluded: [:add_to_reading_list, :print, :air_drop]
) do |activity_type, completed|
  puts "completed with activity: #{activity_type} - finished?: #{completed}"
end

Built in activities that can be passed to the excluded option are defined as UIActivity class UIActivityType constants:

:post_to_facebook
:post_to_twitter
:post_to_weibo
:message
:mail
:print
:copy_to_pasteboard
:assign_to_contact
:save_to_camera_roll
:add_to_reading_list
:post_to_flickr
:post_to_vimeo
:post_to_tencent_weibo
:air_drop

HTTP

BW::HTTP wraps NSURLRequest, NSURLConnection and friends to provide Ruby developers with a more familiar and easier to use API. The API uses async calls and blocks to stay as simple as possible.

To enable it add the following require line to your Rakefile:

require 'bubble-wrap/http'

Usage example:

BW::HTTP.get("https://api.github.com/users/mattetti") do |response|
  p response.body.to_str
end

BW::HTTP.get("https://api.github.com/users/mattetti", {credentials: {username: 'matt', password: 'aimonetti'}}) do |response|
  p response.body.to_str # prints the response's body
end

data = {first_name: 'Matt', last_name: 'Aimonetti'}
BW::HTTP.post("http://foo.bar.com/", {payload: data}) do |response|
  if response.ok?
    json = BW::JSON.parse(response.body.to_str)
    p json['id']
  elsif response.status_code.to_s =~ /40\d/
    App.alert("Login failed")
  else
    App.alert(response.error_message)
  end
end

To upload files to a server, provide a files: hash:

data = {token: "some-api-token"}
avatar_data = UIImagePNGRepresentation(UIImage.imageNamed("some-image"))
avatar = { data: avatar_data, filename: "some-image.png", content_type: "image/png" }

BW::HTTP.post("http://foo.bar.com/", {payload: data}, files: { avatar: avatar }) do |response|
  if response.ok?
    # files are uploaded
  end
end

A :download_progress option can also be passed. The expected object would be a Proc that takes two arguments: a float representing the amount of data currently received and another float representing the total amount of data expected.

Connections can also be cancelled. Just keep a refrence,

@conn = BW::HTTP.get("https://api.github.com/users/mattetti") do |response|
  p response.body.to_str
end

and send the cancel method to it asynchronously as desired. The block will not be executed.

@conn.cancel

Gotchas

Because of how RubyMotion currently works, you sometimes need to assign objects as @instance_variables in order to retain their callbacks.

For example:

class HttpClient
  def get_user(user_id, &callback)
    BW::HTTP.get(user_url(user_id)) do |response|
      # ..
    end
  end
end

This class should be invoked in your code as:

@http_client = HttpClient.new
@http_client.get_user(user_id) do |user|
  # ..
end

(instead of doing an instance-variable-less HttpClient.new.get_user)

RSS Parser

Since: > version 1.0.0

The RSS Parser provides an easy interface to consume RSS feeds in an asynchronous (non blocking) way.

feed_parser = BW::RSSParser.new("http://feeds2.feedburner.com/sdrbpodcast")
feed_parser.parse do |item|
  # called asynchronously as items get parsed
  p item.title
end

The yielded RSS item is of type RSSParser::RSSItem and has the following attributes:

• title
• description
• link
• guid
• pubDate
• enclosure

The item can be converted into a hash by calling to_hash on it.

Delegate

Since: > version 1.0.0

You can also designate a delegate to the parser and implement change state callbacks:

feed_parser = BW::RSSParser.new("http://feeds.feedburner.com/sdrbpodcast")
feed_parser.delegate = self
feed_parser.parse do |item|
  p item.title
end

# Delegate method
def when_parser_initializes
  p "The parser is ready!"
end

def when_parser_parses
  p "The parser started parsing the document"
end

def when_parser_is_done
  p "The feed is entirely parsed, congratulations!"
end

def when_parser_errors
  p "The parser encountered an error"
  ns_error = feed_parser.parserError
  p ns_error.localizedDescription
end

These delegate methods are optional, however, you might find the when_parser_is_done callback useful if you collected all the items and want to process all at once for instance.

Parsing a remote content or actual data

You have the choice to initialize a parser instance with a string representing an URL, an instance of NSURL or my specifying that the passed param is some data to parse directly.

# string representing an url:
feed_parser = BW::RSSParser.new("http://feeds2.feedburner.com/sdrbpodcast")
# a NSURL instance:
url =  NSURL.alloc.initWithString("http://matt.aimonetti.net/atom.xml")
feed_parser = BW::RSSParser.new(url)
# Some data
feed = File.read('atom.xml')
feed_parser = BW::RSSParser.new(feed, true)

Reactor

Since: > version 1.0.0

BW::Reactor is a simplified, mostly complete implementation of the Event Machine API. In fact BW::Reactor is aliased to EM in the runtime environment.

Deferables

BubbleWrap provides both a Deferrable mixin and a DefaultDeferrable class, which simply mixes in deferrable behaviour if you don't want to implement your own.

A deferrable is an object with four states: unknown, successful, failure and timeout. When you initially create a deferrable it is in an unknown state, however you can assign callbacks to be run when the object changes to either successful or failure state.

Using delegate, errback_delegate and callback_delegate you can link deferrables together.

By default, callbacks will be made on the thread that the deferrable succeeds/fails on. For multithreaded environments, it can be useful to use EM::ThreadAwareDeferrable so that callbacks will be made on the threads they are declared on.

Success

> d = EM::DefaultDeferrable.new
=> #<BW::Reactor::DefaultDeferrable:0x6d859a0>
> d.callback { |what| puts "Great #{what}!" }
=> [#<Proc:0x6d8a1e0>]
> d.succeed "justice"
Great justice!
=> nil

Failure

> d = EM::DefaultDeferrable.new
=> #<BW::Reactor::DefaultDeferrable:0x8bf3ee0>
> d.errback { |what| puts "Great #{what}!" }
=> [#<Proc:0x8bf3ef0>]
> d.fail "sadness"
Great sadness!
=> nil

Delegate

> d = EM::DefaultDeferrable.new
=> #<BW::Reactor::DefaultDeferrable:0x8bf3ee0>
> delegate = EM::DefaultDeferrable.new
=> #<BW::Reactor::DefaultDeferrable:0x8bf5910>
> d.delegate delegate
=> #<BW::Reactor::DefaultDeferrable:0x8bf3ee0>
> delegate.callback { |*args| puts args }
=> [#<Proc:0x8bf3ef0>]
> d.succeed :passed
=> nil
=> [:passed]

ThreadAwareDeferrable

> d = EM::ThreadAwareDeferrable.new
=> #<BW::Reactor::ThreadAwareDeferrable:0x8bf3ee0>

> queue = Dispatch::Queue.new(:deferrable.to_s)
> queue.async do 
>   d.callback do |*args|
>     Dispatch::Queue.current == queue
>     => true # this is normally false
>   end
> end
> d.succeed true

Timeout

> d = EM::DefaultDeferrable.new
=> #<BW::Reactor::DefaultDeferrable:0x8bf5910>
> d.errback { puts "Great scott!" }
=> [#<Proc:0x8bf6350>]
> d.timeout 2
=> #<BW::Reactor::Timer:0x6d920a0 @timer=#<__NSCFTimer:0x6d91990>>
# wait...
> Great scott!

Timers

All timers can be cancelled using EM.cancel_timer.

One-shot timers

> EM.add_timer 1.0 do
>   puts "Great scott!"
> end
=> 146335904
> Great scott!

Periodic timers

> count = 0
=> 0
> timer = EM.add_periodic_timer 1.0 do
>   count = count + 1
>   puts "Great scott!"
>   (count < 10) || EM.cancel_timer(timer)
> end
=> 146046832
> Great scott!
Great scott!
Great scott!
Great scott!
Great scott!
Great scott!
Great scott!
Great scott!
Great scott!
Great scott!

Scheduling operations

You can use EM.schedule to schedule blocks to be executed asynchronously. BubbleWrap deviates from the EventMachine API here in that it also provides EM.schedule_on_main which makes sure that the task is run asynchronously, but on the application's main thread - this is necessary if you are updating the user interface.

> EM.schedule { puts Thread.current.object_id }
146027920
=> nil
> EM.schedule_on_main { puts Thread.current.object_id }
112222480
=> nil

Deferrable operations

You can also use EM.defer in much the same way as EM.schedule with one important difference, you can pass in a second proc which will be called when the first has completed, and be passed it's result as an argument. Just like EM.schedule, EM.defer also has an EM.defer_on_main version.

> operation = proc { 88 }
=> #<Proc:0x6d763c0>
> callback = proc { |speed| puts speed >= 88 ? "Time travel!" : "Conventional travel!" }
=> #<Proc:0x8bd3910>
> EM.defer(operation, callback)
=> nil
Time travel!

Events

Although not part of the EventMachine API, BubbleWrap provides an Eventable mixin for use instrumenting objects with simple event triggering behaviour. BW::Reactor uses this behind the scenes in several places, and as it's a very handy idiom it is available as a public API.

> o = Class.new { include EM::Eventable }.new
=> #<#<Class:0xab63f00>:0xab64430>
> o.on(:november_5_1955) { puts "Ow!" }
=> [#<Proc:0xad9bf00>]
> flux = proc{ puts "Flux capacitor!" }
=> #<Proc:0xab630f0>
> o.on(:november_5_1955, &flux)
=> [#<Proc:0xad9bf00>, #<Proc:0xab630f0>]
> o.trigger(:november_5_1955)
Ow!
Flux capacitor!
=> [nil, nil]
> o.off(:november_5_1955, &flux)
=> #<Proc:0xab630f0>
> o.trigger(:november_5_1955)
Ow!
=> [nil]

Suggestions?

Do you have a suggestion for a specific wrapper? Feel free to open an issue/ticket and tell us about what you are after. If you have a wrapper/helper you are using and are thinking that others might enjoy, please send a pull request (with tests if possible).