iOS程序进入后台后仍运行定时器NSTimer

1、步骤一：在Info.plist中，添加\"Required background modes\"键，value为：App plays audio

步骤二：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];

// Override point for customization after application launch.

NSError *setCategoryErr = nil; NSError *activationErr = nil; [[AVAudioSession sharedInstance]

setCategory: AVAudioSessionCategoryPlayback error: &setCategoryErr];

[[AVAudioSession sharedInstance] setActive: YES

error: &activationErr];

self.window.backgroundColor = [UIColor whiteColor]; [self.window makeKeyAndVisible]; return YES; }

步骤三：将以下代码添加到appDelegate文件中的- (void)applicationDidEnterBackground:(UIApplication *)application函数，也可添加到在具体类中注册的应用进入后台后的通知方法 - (void)applicationDidEnterBackground:(UIApplication *)application{

UIApplication* app = [UIApplication sharedApplication];

__block UIBackgroundTaskIdentifier bgTask;

bgTask = [app beginBackgroundTaskWithExpirationHandle

r:^{

dispatch_async(dispatch_get_main_queue(), ^{ if (bgTask != UIBackgroundTaskInvalid) {

bgTask = UIBackgroundTaskInvalid; } }); }];

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

dispatch_async(dispatch_get_main_queue(), ^{ if (bgTask != UIBackgroundTaskInvalid) {

bgTask = UIBackgroundTaskInvalid; } }); }); }

完成以上步骤你会发现，程序进入后台后仍可运行定时器！