iOS程序进入后台后仍运行定时器NSTimer

iOS常驻后台

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];returnYES;

}

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 beginBackgroundTaskWithExpirationHandler:^{

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！