iOS程序进入后台后仍运行定时器NSTimer

谁借莪１个温暖的怀抱￠ 2022-06-02 11:55 176阅读 0赞

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

![Image 1][]

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

![复制代码][copycode.gif]

- (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;
                }
            });
        });
    }

![复制代码][copycode.gif]

完成以上步骤你会发现，程序进入后台后仍可运行定时器！

[Image 1]: 
[copycode.gif]: /images/20220602/f1fc1dfa77df410d986b6228b156465a.png