當App進入到后臺時候，會自動調用AppDelegate代理方法
- (void)applicationDidEnterBackground:(UIApplication *)application；接下來就是在applicationDidEnterBackground的代理方法中設置
- (void)applicationDidEnterBackground:(UIApplication *)application { [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:nil]; [self backTask];}- (void)backTask{ if ([[UIApplication sharedApplication] backgroundTimeRemaining] < 61.0) { [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:nil]; } NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:2 target:self selector:@selector(test) userInfo:nil repeats:YES]; self.timer = timer; self.i = 1;}- (void)test{ NSLog(@"這是第幾次輸出====%d",self.i); self.i++ ;}這樣做就可以是App進入到后臺仍可以運行，看到控制輸出臺上一直打印。
新聞熱點
疑難解答
