Notice: This project isn't under active development.
I recomend you trying one of the the other libraries like:

This projects allows you to quickly and easily fetch data from openweathermap.org.
The methods for getting the daily forecast have changed names. So instead of: dailyForecastWeatherByCityName:withCount:withCallback:
they are now called: dailyForecastWeatherByCityName:withCount:andCallback:
Added new methods for setting the lang parameter to the api:
 - (void) setLangWithPreferedLanguage;
 - (void) setLang:(NSString *) lang;
 - (NSString *) lang;
The method setLangWithPreferedLanguage sets the lang parameter according to the prefered language on the phone.
Using the API is really simple if you have CocoaPods installed.
- 
Add the dependency to your Podfilepod 'OpenWeatherMapAPI', '~> 0.0.5' 
- 
Include the header #import "OWMWeatherAPI.h".
- 
Setup the api: // Setup weather api OWMWeatherAPI *weatherAPI = [[OWMWeatherAPI alloc] initWithAPIKey:@"YOUR-API-KEY"]; 
- 
Select the default temperature format (defaults to Celsius) [weatherAPI setTemperatureFormat:kOWMTempCelcius]; 
The api is at this time just simple wrapper for the http-api. So to get the current weather for
the city Odense you can call it like this:
[weatherAPI currentWeatherByCityName:@"Odense" withCallback:^(NSError *error, NSDictionary *result) {
    if (error) {
        // handle the error
        return;
    }
    // The data is ready
    NSString *cityName = result[@"name"];
    NSNumber *currentTemp = result[@"main"][@"temp"];
}]The result data is a NSDictionary that looks like
this (json):
    {
        coord: {
            lon: 10.38831,
            lat: 55.395939
        },
        sys: {
            country: "DK",
            sunrise: 1371695759, // this is an NSDate
            sunset: 1371758660   // this is also converted to a NSDate
        },
        weather: [
            {
                id: 800,
                main: "Clear",
                description: "Sky is Clear",
                icon: "01d"
            }
        ],
        base: "global stations",
        main: {
            temp: 295.006,      // this is the the temperature format you´ve selected
            temp_min: 295.006,  //                 --"--
            temp_max: 295.006,  //                 --"--
            pressure: 1020.58,
            sea_level: 1023.73,
            grnd_level: 1020.58,
            humidity: 80
        },
        wind: {
            speed: 6.47,
            deg: 40.0018
        },
        clouds: {
            all: 0
        },
        dt: 1371756382,
        id: 2615876,
        name: "Odense",
        cod: 200
    }See an example in the OWMViewController.m file.
The following methods are available at this time:
current weather by city name:
    -(void) currentWeatherByCityName:(NSString *) name
                        withCallback:( void (^)( NSError* error, NSDictionary *result ) )callback;current weather by coordinate:
    -(void) currentWeatherByCoordinate:(CLLocationCoordinate2D) coordinate
                          withCallback:( void (^)( NSError* error, NSDictionary *result ) )callback;current weather by city id:
    -(void) currentWeatherByCityId:(NSString *) cityId
                      withCallback:( void (^)( NSError* error, NSDictionary *result ) )callback;forecast by city name:
    -(void) forecastWeatherByCityName:(NSString *) name
                         withCallback:( void (^)( NSError* error, NSDictionary *result ) )callback;forecast by coordinate:
    -(void) forecastWeatherByCoordinate:(CLLocationCoordinate2D) coordinate
                           withCallback:( void (^)( NSError* error, NSDictionary *result ) )callback;forecast by city id:
    -(void) forecastWeatherByCityId:(NSString *) cityId
                       withCallback:( void (^)( NSError* error, NSDictionary *result ) )callback;daily forecast by city name:
    -(void) dailyForecastWeatherByCityName:(NSString *) name
                                 withCount:(int) count
                              andCallback:( void (^)( NSError* error, NSDictionary *result ) )callback;daily forecast by coordinates:
    -(void) dailyForecastWeatherByCoordinate:(CLLocationCoordinate2D) coordinate
                                   withCount:(int) count
                                andCallback:( void (^)( NSError* error, NSDictionary *result ) )callback;
daily forecast by city id:
   -(void) dailyForecastWeatherByCityId:(NSString *) cityId
                              withCount:(int) count
                           andCallback:( void (^)( NSError* error, NSDictionary *result ) )callback;search for a city by name:
   -(void) searchForCityName:(NSString *) name
                   withCount:(int) count
                andCallback:( void (^)( NSError* error, NSDictionary *result ) )callback;