Sheet can not be presented because the view is not in a window的解决办法,和window的简单使用

Sheet can not be presented because the view is not in a window，顺便在stackoverflow上找了答案，希望能给大家带来帮助，在此感谢我的朋友们。

1.

UIWindow* window =[[UIApplication sharedApplication] keyWindow];

if([window.subviews containsObject:self.view])

{[emailSheet showInView:self.view];}

else{[emailSheet showInView:window];}

2.

[actionSheet showInView:[[[[UIApplication sharedApplication] keyWindow] subviews] lastObject]];