iOS延迟关闭

// AppDelegate.h文件
@property (assign, nonatomic) UIBackgroundTaskIdentifier backgroundUpdateTask;

// AppDelegate.m文件
- (void)applicationDidEnterBackground:(UIApplication *)application
{
    [self beingBackgroundUpdateTask];
    // 在这里加上你需要长久运行的代码
    [self endBackgroundUpdateTask];
}

- (void)beingBackgroundUpdateTask
{
    self.backgroundUpdateTask = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{
        [self endBackgroundUpdateTask];
    }];
}

- (void)endBackgroundUpdateTask
{
    [[UIApplication sharedApplication] endBackgroundTask: self.backgroundUpdateTask];
    self.backgroundUpdateTask = UIBackgroundTaskInvalid;
}