我使用这段代码来初始化 MBProgressHUD
UIWindow *window = [[UIApplication sharedApplication] keyWindow]
_hud = [[MBProgressHUD alloc]initWithWindow:window];
_hud.dimBackground = bDim;
_hud.labelText = message;
[window addSubview:_hud];
[_hud show:YES];
但有时 _hud 不显示在窗口中?任何人都让我知道我在这里缺少什么?谢谢!