iOS版 - backgroundTimeRemaining值不显示期望是什么 [英] iOS - backgroundTimeRemaining value not showing what expected

问题描述

我想检查 backgroundTimeRemaining 的价值，但我得到一个非常大的数字。该属性的值被认为是相应于10分钟aprox的，而苹果文档中<一个i`ve读href=\"http://developer.apple.com/library/ios/#DOCUMENTATION/UIKit/Reference/UIApplication_Class/Reference/Reference.html\">here这样的值大时，应用程序是在前台。不过，我得到一个较大的值，即使在背景：

I'm trying to check the value of backgroundTimeRemaining, but I get a very large number. The value of the property is supposed to be the corresponding to 10 min aprox, and i`ve read in Apple documentation here that such value is large when the app is in the foreground. However, I get a large value even when in background:

- (void)applicationDidEnterBackground:(UIApplication *)application
{
   bgTask = [application beginBackgroundTaskWithExpirationHandler:^{
      [application endBackgroundTask:bgTask];
      bgTask = UIBackgroundTaskInvalid;
   }];

   // Background task
   NSTimeInterval timeRemaining = [UIApplication sharedApplication].backgroundTimeRemaining;
   NSLog(@"Background time remaining: %f seconds (%d mins)", timeRemaining, (int)(timeRemaining / 60));

   dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
      NSTimeInterval timeRemaining = [UIApplication sharedApplication].backgroundTimeRemaining;
      NSLog(@"Background time remaining: %f seconds (%d mins)", timeRemaining, (int)(timeRemaining / 60));

      // Perform task

      // Finished
      if (bgTask != UIBackgroundTaskInvalid) {
         [application endBackgroundTask:bgTask];
         bgTask = UIBackgroundTaskInvalid;
      }
  });

  // Start location manager
  if ([CLLocationManager locationServicesEnabled]) {          
     [locationManager startUpdatingLocation];
  }
}

还有什么我缺少什么？在此先感谢

What could am I missing? Thanks in advance

推荐答案

根据X code运行时，看门狗定时器被禁止。

The watchdog timer is disabled when running from Xcode.

我无关运行时，大多得到合理的值（即600），但我仍然得到偶尔的怪异值。

I mostly get sensible values (ie. 600) when running unconnected, but I still get the occasional weird value.

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