收到通知以后，怎样判断应用程序在前台还是后台？

Question

应用程序不管在后台还是前台都会执行- (void)application:(UIApplication *)application
didReceiveRemoteNotification:(NSDictionary *)userInfo
fetchCompletionHandler:(void
(^)(UIBackgroundFetchResult))completionHandler

                    那怎么在这个方法里判断应用程序在前台还是在后台呢？

Answer 1

[UIApplication sharedApplication].applicationState == UIApplicationStateActive
这是在前台
UIApplicationStateBackground 这是在后台

Answer 2

在AppDelegate中有如下几个方法, 用一个flag标记是否是前台
- (void)applicationDidEnterBackground:(UIApplication *)application
{
//程序进入后台
flag = NO;
}

• (void)applicationDidBecomeActive:(UIApplication *)application
  {
  //程序进入前台
  flag = YES;
  }