1、MBProgressHUD *HUD = [[MBProgressHUDalloc] initWithWindow:[UIApplicationsharedApplication].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？？？