refactor(macos): migrate to objc2

[pewsheen]

Issue: #1239

Roadmap

• Remove objc dependency
• Merge dev branch
• Declare Custom Class
  • WryWebView
  • {}URLSchemeHandler (We need to create it dynamically)
  • WebViewDelegate -> WryWebViewDelegate
  • DocumentTitleChangedDelegate
  • WryNavigationDelegate
  • WryDownloadDelegate
  • WebViewUIDelegate -> WryWebViewUIDelegate
  • WryWebViewParent
• Test Functionality
• Update Tauri to use wry with objc2 pewsheen/refactor/wry-objc2

Functionality Test:

• Window (single webview)
• Window (multiple webviews)
• Window iOS
• PerformKeyEquivalent (menu shortcut)
• Picture in picture
• Fullscreen (feature = fullscreen)
• Document title changed handler
• Navigation Policy (download handler?)
• [mac] Reparent
• UIDelegate
  • File upload
  • Media capture permission
• [ios] setAllowsInlineMediaPlayback (not merged yet, in dev)
• [mac] Synthetic mouse event
• [mac] Tab focuses links
• with_*
  • [mac] with_back_forward_navigation_gestures
  • with_transparent
  • with_visible
  • with_autoplay (false is not working, dev as well)
  • with_initialization_script
  • with_custom_protocol
  • with_asynchronous_custom_protocol
  • with_ipc_handler
  • [mac] with_drag_drop_handler
  • with_url_and_headers
  • with_url
  • with_headers
  • with_html
  • with_user_agent
  • with_devtools
  • with_navigation_handler
  • with_download_started_handler
  • with_download_completed_handler
  • with_new_window_req_handler
  • [mac] with_accept_first_mouse
  • with_document_title_changed_handler
  • with_incognito
  • with_on_page_load_handler
  • with_proxy_config (feature = mac-proxy)
  • with_bounds (child webview)
• pub fn
  • [mac] print
  • url
  • load_url
  • load_url_with_headers
  • eval
  • clear_all_browsing_data
  • [mac] open_devtools
  • [mac] close_devtools
  • [mac] is_devtools_open
  • zoom
  • bounds
  • [mac] set_bounds (child webview)
  • set_visible
  • focus
  • url_from_webview
  • platform_webview_version

Issues

• Async custom protocol has lifetime issue and might cause panic: 2fb6be9
• (WIP) objc2-web-kit not support WKWebView on iOS. We need this so we can continue the migration.
  • iOS/tvOS/watchOS/visionOS support in framework crates madsmtm/objc2#408
  • Make objc2_web_kit::WKWebView supports iOS madsmtm/objc2#637
• Any way to catch NSException so we can recover from some situations? I'm using catch_unwind now for the exception, but I think this is not ideal.

if catch_unwind(|| {
  config_unwind_safe.setURLSchemeHandler_forURLScheme(
    Some(&*(handler_unwind_safe.cast::<ProtocolObject<dyn WKURLSchemeHandler>>())),
    &NSString::from_str(&name),
  );
})

• (WIP) tauri-runtime-wry need to use objc2 as well
  • https://github.com/pewsheen/tauri/tree/refactor/wry-objc2

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[madsmtm]

Gave it a cursory look, great overall, really nice to see objc2 used effectively, gives me motivation to fix the places where it isn't working!

[madsmtm]

Should only be enabled under [target."cfg(target_os = \"macos\")".dependencies]. Reversed for objc2-ui-kit.

[madsmtm]

objc2-web-kit not support WKWebView on iOS (madsmtm/objc2#637)

I think the easiest approach for now might be for you to copy objc2-web-kit's definition from the source into a file in this repo, remove the #[cfg(feature = "objc2-app-kit")], change NSWindow to UIWindow, and import it from that file on iOS instead of from objc2-web-kit.

[madsmtm]

If you change these to take dyn Fn(...) + 'static instead, then you don't need to into_raw and from_raw it, and it also becomes sound. (At least I think that's how the lifetimes work here? I can never remember...)

Also, Box<dyn FnMut(...)> really isn't possible in Objective-C classes, you'll have to wrap it in a RefCell.

Suggested change

	download_started_handler: Option<Box<dyn FnMut(String, &mut PathBuf) -> bool>>,
	download_completed_handler: Option<Rc<dyn Fn(String, Option<PathBuf>, bool)>>,
	download_started_handler: Option<RefCell<Box<dyn FnMut(String, &mut PathBuf) -> bool + 'static>>>,
	download_completed_handler: Option<Rc<dyn Fn(String, Option<PathBuf>, bool) + 'static>>,

[pewsheen]

Also, Box<dyn FnMut(...)> really isn't possible in Objective-C classes, you'll have to wrap it in a RefCell.

Could you explain more about this? I am curious how this work

[madsmtm]

Objective-C classes require interior mutability (&self), so while you can store Box<dyn FnMut(...)> in them, it'd be useless, as it requires a mutable reference (&mut self) to call the closure.

It'd be kinda like using Rc<Box<dyn FnMut(...)>> - try it out, it won't work unless you introduce RefCell or similar forms of interior mutability.

Just to clear up any confusion, Box<dyn Fn(...)> is fine, it's the FnMut that's problematic.

[pewsheen]

Note: iOS can now be built and run on the iOS simulator from Tauri (it requires some modification in Tauri to use objc2). It's still WIP for testing some functionalities and organizing the code.

https://github.com/pewsheen/tauri/tree/refactor/wry-objc2