1、MBProgressHUD *HUD = [[MBProgressHUD
alloc] initWithWindow:[UIApplication
sharedApplication].keyWindow];

2、MBProgressHUD *HUD = [MBProgressHUD showHUDAddedTo:[[UIApplication sharedApplication].windows objectAtIndex:1] animated:YES];

[self.view.window addSubview:HUD];

HUD.labelText = kVerifyRefreshing;

第一种动画失效，不知啥原因？？？