Descargar imagen asíncronamente
- ( void )downloadImageWithURL:( NSURL *)url completionBlock:( void (^)( BOOL succeeded, UIImage *image))completionBlock { NSMutableURLRequest *request = [ NSMutableURLRequest requestWithURL :url]; [ NSURLConnection sendAsynchronousRequest :request queue :[ NSOperationQueue mainQueue ] completionHandler :^( NSURLResponse *response, NSData *data, NSError *error) { if ( !error ) { ...