NSScreencast Episode #92 Background Fetch

Background Fetch - NSScreencast

Weather appでlocationからの検索をバックグラウンドを使って実行

• weather app
  • search by location
• WeatherFetcher
  • sharedInstance
  • cachedResult
• needsRefresh
  • NSTimeInterval interval = abs([lastUpdated timeIntervalSinceNow]);
  • timePassed
• application capability
  • background fetch
• app delegate
  • [application setMinimumBackgroundFetchInterval:UIApplicationBackgroundFetchIntervalMinimum];
    • UIApplicationBackgroundFetchIntervalMinimum
    • UIApplicationBackgroundFetchIntervalNever
  • performFetchWithCompletionHandler
    • cachedResult
• testing
  • breakponit with sound
  • duplicate scheme
    • check background fetching
• fetch twice problem
  • not reload data in background
    • applicationState] == UIApplicationStateActive
• problem value not refreshed on next view loading
  • [NSNotificationCenter defaultCenter] postNotificationName:@"WeatherUpdated"
  • in viewDidLoad
    • [NSNotificationCenter defaultCenter] addObserver:self selector:@selector(onBackgroundUpdate:) name:@"WeatherUpdated"
    • onBackgroundUpdate
  • snapshot has new data
  • applicationDidBecomeActive