對(duì)于 UITabarController管理的導(dǎo)航控制器的根界面，如果加入動(dòng)畫，你會(huì)發(fā)現(xiàn)，當(dāng)應(yīng)用退出到后臺(tái)，然后進(jìn)入到前臺(tái)，你就會(huì)發(fā)現(xiàn)動(dòng)畫停止了。解決辦法就是添加通知監(jiān)聽?wèi)?yīng)用進(jìn)入前臺(tái)，進(jìn)入活躍狀態(tài)。

     [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(appDidEnterPlayground) name:UIApplicationDidBecomeActiveNotification object:nil];
}
-(void)appDidEnterPlayground{
    [self.heroBtn.layer removeAllAnimations];
     [self.heroBtn.layer addAnimation:[self groupAnimation] forKey:nil];
}