Download weather forecast #AppSoc02122014

gistfile1.m

- (void)downloadWeatherForecast {
    // constant representing the number of seconds in a day
    const int kSecondsInDay = 60 * 60 * 24;
    
    // the url of the weather api
    NSString *const kWeatherForecastURL = @"http://api.openweathermap.org/data/2.5/forecast/daily?q=London&mode=json&units=metric&cnt=14";
    
    // create a url request for the weather api url
    NSURLRequest *request = [[NSURLRequest alloc] initWithURL:[NSURL URLWithString:kWeatherForecastURL]];
    
    // send the request without blocking the main ui thread
    [NSURLConnection sendAsynchronousRequest:request
                                       queue:[NSOperationQueue mainQueue]
                           completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {
                               // exit if there is a connection error
                               if (connectionError) {
                                   return;
                               }
                               
                               NSError *error;
                               // parse the json response
                               NSDictionary *json = [NSJSONSerialization JSONObjectWithData:data
                                                                                    options:0
                                                                                      error:&error];
                               // if there was a parsing error (invalid json) then exit
                               if (error) {
                                   return;
                               }
                               
                               // date formatter to get the day name from a date
                               NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
                               [dateFormatter setDateFormat:@"EEEE"];
                               
                               // for each weather forecast store the day
                               for (int i = 0; i < [json[@"list"] count]; i++) {
                                   NSMutableDictionary *dayInfo = [NSMutableDictionary dictionary];
                                   
                                   dayInfo[@"name"] = [dateFormatter stringFromDate:[[NSDate date] dateByAddingTimeInterval: kSecondsInDay * i]];
                                   dayInfo[@"forecast"] = json[@"list"][i];
                                   
                                   [self.daysWeather addObject:dayInfo];
                               }
                               
                               // refresh the content of the table view
                               [self.tableView reloadData];
                               
                           }];
}