在iOS中对后台线程执行任务，即使应用程序进入后台也继续执行：

如何在后台线程上执行？ 即使用户按下主页按钮，执行也应在后台继续。

Answer 1

将这些属性添加到.h文件中

@property (nonatomic, strong) NSTimer *updateTimer; @property (nonatomic) UIBackgroundTaskIdentifier backgroundTask; 

现在假设您对按钮 – > btnStartClicked有一个操作，那么您的方法将是：

 -(IBAction)btnStartClicked:(UIButton *)sender { self.updateTimer = [NSTimer scheduledTimerWithTimeInterval:0.5 target:self selector:@selector(calculateNextNumber) userInfo:nil repeats:YES]; self.backgroundTask = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{ NSLog(@"Background handler called. Not running background tasks anymore."); [[UIApplication sharedApplication] endBackgroundTask:self.backgroundTask]; self.backgroundTask = UIBackgroundTaskInvalid; }]; } -(void)calculateNextNumber{ @autoreleasepool { // this will be executed no matter app is in foreground or background } } 

如果你需要停止使用这个方法，

 - (IBAction)btnStopClicked:(UIButton *)sender { [self.updateTimer invalidate]; self.updateTimer = nil; if (self.backgroundTask != UIBackgroundTaskInvalid) { [[UIApplication sharedApplication] endBackgroundTask:self.backgroundTask]; self.backgroundTask = UIBackgroundTaskInvalid; } i = 0; }