加载符号没有在button点击出现

Question

-(IBAction)addtocontacts:(id)sender
{
    HUD = [MBProgressHUD showHUDAddedTo:self.view animated:YES];
    HUD.labelText = NSLocalizedString(@"Saving_data", @"");

    //added my validation here
   [self performSelectorInBackground:@selector(insertDetails) withObject:nil];
}
-(void) insertDetails
{
  //save contact details in database
[HUD hide:YES];
    UIAlertView *alertview=[[UIAlertView alloc]initWithTitle:@"" message:@"Contact account details added" delegate:self cancelButtonTitle:@"Ok" otherButtonTitles:nil, nil];
[alertview show];
}

我在savebutton点击添加了加载符号，但是没成功，怎么让符号出现，到了有警告信息时再消失？

Answer 1

performSelectorInBackground这里马上就去运行了，同时[HUD hide:YES];又让loading动画隐藏了。
你可以试着注释掉[HUD hide:YES];
另外，有关UI的操作，最好都不要放到Background线程里，因此performSelectorInBackground最好改为performSelector