例 1
UIViewController *vc = [UIViewController new];
[self.navigationController pushViewController:vc animated:YES];
上述代码推出界面会卡顿
解决办法：
UIViewController *vc = [UIViewController new];
vc.view.backgroundColor = [UIColor 推出时你想要的控制器View的颜色]
/**
* 如
*/
vc.view.backgroundColor = [UIColor whiteColor];
[self.navigationController pushViewController:vc animated:YES];
