弹出视图控制器时，MKMapView使应用程序崩溃

问题描述：

我有一个带有MKMapView的视图控制器，该控制器调用

I have a view controller with an MKMapView that calls

[self.mapView setRegion:region animated:YES];

将地图从A重新定位到B.

which repositions the map from A to B.

将保存MKMapView的视图控制器设置为委托，并在

The view controller which holds the MKMapView is set as the delegate and in

- (void)mapView:(MKMapView *)mapView regionDidChangeAnimated:(BOOL)animated

我有一些代码将触发另一个setRegion:animated:到MKMapView，以便地图将自动放大到新位置.

I have some code that will trigger another setRegion:animated: to the MKMapView so that the map will zoom in on the new position automatically.

如果我popViewControllerAnimated，一切都可以正常工作:MKMapView动画平移和缩放后，视图控制器.

Everything works fine if I popViewControllerAnimated: the view controller AFTER the MKMapView animation is done panning and zooming.

但是，当我尝试popViewControllerAnimated时:当前的视图控制器，当MKMapView运行其动画时，应用程序崩溃，并显示消息发送到已释放的实例".

However, when I try to popViewControllerAnimated: the current view controller WHILE the MKMapView is running it's animation, the app crashes with "message sent to deallocated instance".

从调试器的外观来看，我认为MKMapView试图从弹出并释放的委托中调用方法.

From the looks of the debugger, I think that MKMapView is trying to call a method from a popped and deallocated delegate.

所以我尝试了

[self.mapView setDelegate:nil];
self.mapView = nil;

在viewDidUnload中没有运气.该应用仍然崩溃.

in viewDidUnload with no luck. The app still crashes consistently.

我唯一想到的就是创建一个单独的新委托类，并从父视图控制器保留该类，以便即使在释放包含它的视图控制器之后，MKMapView也会有一个要调用的委托.

The only thing I could think of was to create a separate new delegate class and retain that class from the parent view controller so that the MKMapView would have a delegate to call even after the view controller that contains it is deallocated.

为什么会这样? 还有其他干净"的选择吗?

Why is this happening? Are there any other "clean" options?

答

一个朋友帮助我得到了这个.

A friend helped me get this one.

我实现了自己的用于弹出视图控制器的方法，而不是使用默认导航控制器的后退按钮.我只需要添加[self.mapView setDelegate:nil];在弹出视图控制器之前.

I implemented my own method for popping the view controller instead of using the default navigation controller's back button. I just had to add [self.mapView setDelegate:nil]; before I popped the view controller.

- (void)goBack
{
    [self.mapView setDelegate:nil];
    [self.navigationController popViewControllerAnimated:YES];
}

弹出视图控制器时，MKMapView使应用程序崩溃

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