iOS 项目一直在后台执行

我后来是这么解决不知道行不行，能够长期的在后台执行

首先我在xx-info.plist 里的 "Required background modes" 里增加"App provides Voice over IP services"

然后在delegate里增加下面代码，原理是进入后台时程序会在600秒那样结束任务，我做的就是在结束任务前新开一个任务。再结束旧任务，这样就一直的在后台执行，希望可能帮助到很多其它的人。我也查了非常久才找到这种方法的。

UIBackgroundTaskIdentifier
backgroundTaskIdentifier;

02	UIBackgroundTaskIdentifier oldBackgroundTaskIdentifier;

03

04	- (BOOL) isMultitaskingSupported{

05

06	BOOL result = NO;

07

08	if ([[UIDevice currentDevice]

09

10	respondsToSelector:@selector(isMultitaskingSupported)]){ result = [[UIDevice currentDevice] isMultitaskingSupported];

11

12

}

13

14	return result;

15

16

}

17

18	- (void) timerMethod:(NSTimer *)paramSender{

19

count++;

20	if (count % 500 == 0) {

21	UIApplication *application = [UIApplication sharedApplication];

22

23	//开启一个新的后台

24

25	backgroundTaskIdentifier = [application beginBackgroundTaskWithExpirationHandler:^{

26

27

}];

28	//结束旧的后台任务

29	[application endBackgroundTask:backgroundTaskIdentifier];

30	oldBackgroundTaskIdentifier = backgroundTaskIdentifier;

31

}

32	NSLog(@"%ld",count);

33

}

34	- (void)applicationDidEnterBackground:(UIApplication *)application

35

{

36	if ([self isMultitaskingSupported] == NO){

37

38

return; }

39	//开启一个后台任务

40

41	backgroundTaskIdentifier = [application beginBackgroundTaskWithExpirationHandler:^{

42

}];

43	oldBackgroundTaskIdentifier = backgroundTaskIdentifier;

44	if ([self.myTimer isValid]) {

45	[self.myTimer invalidate];

46

}

47	self.myTimer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(timerMethod:) userInfo:nil repeats:YES];

48

}

49

50	- (void)applicationWillEnterForeground:(UIApplication *)application

51

{

52	if (backgroundTaskIdentifier != UIBackgroundTaskInvalid){

53	[application endBackgroundTask:backgroundTaskIdentifier];

54	if ([self.myTimer isValid]) {

55	[self.myTimer invalidate];

56

}

57

}

58

}

59

60	- (void)applicationWillEnterForeground:(UIApplication *)application

61

{

62	if (backgroundTaskIdentifier != UIBackgroundTaskInvalid){

63	[application endBackgroundTask:backgroundTaskIdentifier];

64	if ([self.myTimer isValid]) {

65	[self.myTimer invalidate];

66

}

67

}

68

}