如何处理自定义UIViewController委托（ARC）？

I have the following code:

我有以下代码：

- (IBAction)mapPressed:(id)sender
{
    MapViewController *mapVC = [[MapViewController alloc] initWithNibName:@"MapViewController" bundle:[NSBundle mainBundle]];
    mapVC.delegate = self;
    [self.navigationController pushViewController:mapVC animated:YES];
}
- (IBAct