How to run NSTimer in background beyond 180sec in iOS 7?

问题

I have tried this but not working more than 180 sec in iOS 7 and Xcode 4.6.2. Please help me

    UIBackgroundTaskIdentifier bgTask = UIBackgroundTaskInvalid;
        UIApplication *app = [UIApplication sharedApplication];
       bgTask = [app beginBackgroundTaskWithExpirationHandler:^{
            [app endBackgroundTask:bgTask];
        }];
        NSTimer  *timer = [NSTimer scheduledTimerWithTimeInterval:20 target:self   selector:@selector(timerMethod) userInfo:nil repeats:YES];
        [[NSRunLoop currentRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
     -(void) timerMethod{

     NSLog(@\"in timerMethod\");
    }

回答1:

Unless you enable one of the Background modes, it is not gonna work.

Why?

• You have around 10 minutes of background execution after this the timer is stopped by ios.

• The timer will not fire after app is locked (iOS7), since ios suspends the foreground app and bgTask will not get fire again.

There is some workarounds, consider to check below question:

iphone - NSTimers in background

Scheduled NSTimer when app is in background?

NSTimer on background IS working

来源：https://stackoverflow.com/questions/22628922/how-to-run-nstimer-in-background-beyond-180sec-in-ios-7