解决方法:
1.在plist文件中将 View controller-based status bar appearance 设置为NO
2.在application:didFinishLaunchingWithOptions:中添加下面代码
[[UIApplication sharedApplication] setStatusBarHidden:YES withAnimation:UIStatusBarAnimationNone];
[[UIApplication sharedApplication] setStatusBarHidden:NO withAnimation:UIStatusBarAnimationNone];