UIPopovercontroller dealloc reached while popover

问题:

I assure you that I did look for an answer in SO for my question but none of them were helpful. Here I got a simple code that should present a UIImagePickerController within a UIPopoverController:

-(void)takePicture:(id)sender{
UIImagePickerController *picker=[[UIImagePickerController alloc] init];
picker.delegate=self;
picker.sourceType=UIImagePickerControllerSourceTypeCamera;
picker.allowsEditing=YES;
UIPopoverController *poc=[[UIPopoverController alloc] 
                            initWithContentViewController:picker];
[poc presentPopoverFromBarButtonItem:bbItem 
            permittedArrowDirections:UIPopoverArrowDirectionAny
                            animated:NO];
}

Now, even from the first time I get [UIPopoveController dealloc] reached while... error and the program crashes. I'm not doing any retain,relase or autoreleases as per ARC. Is there any special consideration with UIPopoverControllers when benefitting from ARC?

回答1:

UIPopoverControllers should always be held in an instance variable. It is a good practice to create a strong property for it.

UPDATE:

As of iOS 8 you should be using UIPopoverPresentationController. Then you don't need to keep a reference to the popover because it is managed by the presentation controller.

Code example (works both on iPhone and iPad):

UIImagePickerController *picker = [[UIImagePickerController alloc] init];
picker.delegate = self;
picker.sourceType = UIImagePickerControllerSourceTypeCamera;
picker.allowsEditing = YES;
picker.modalPresentationStyle = UIModalPresentationPopover;
UIPopoverPresentationController* popoverPC = picker.popoverPresentationController;
popoverPC.barButtonItem = bbItem;
popoverPC.permittedArrowDirections = UIPopoverArrowDirectionAny;
[self presentViewController:picker animated:YES completion:nil];

回答2:

When the function exits there are no other reference to the popover controller, so it's deallocated too early.

Try adding it as a member of your class instead.

Tim

回答3:

Adding what @phix23 answered, create *poc property like this:

@property (nonatomic, retain) IBOutlet UIPopoverController *poc;

and then change

UIPopoverController *poc = [[UIPopoverController alloc] 
                            initWithContentViewController:picker];

for

self.poc = [[UIPopoverController alloc] 
                            initWithContentViewController:picker];