objective-c - UIPopoverController的奇怪错误

Question

我正在尝试使用UIImagePickerController从用户在其iPhone / iPad上的照片中抓取照片。该代码在iPhone上运行良好，但是当我在iPad上运行时，调试器将显示消息“由于未捕获的异常'NSGenericException'而终止应用程序，原因:'-[UIPopoverController dealloc]在弹出窗口仍然可见的情况下到达。”。我对Objective-C还是很陌生，所以我不确定是什么原因导致的，我没有取消分配任何东西，并且打开了ARC。这是我的代码:
ViewController.m

#import "PhotoViewController.h"


@implementation PhotoViewController
@synthesize grabButton;
@synthesize image;
@synthesize imgPicker;

- (IBAction)grabImage {
    if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPad) {
        UIPopoverController *popover = [[UIPopoverController alloc] initWithContentViewController:imgPicker];
        [popover presentPopoverFromRect:self.image.bounds inView:self.image permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES];

    } else {
        [self presentModalViewController:imgPicker animated:YES];
    }
}

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingImage:(UIImage *)img editingInfo:(NSDictionary *)editInfo {
    image.image = img;
    [[picker parentViewController] dismissModalViewControllerAnimated:YES];
}

- (void)viewDidLoad
{
    self.imgPicker = [[UIImagePickerController alloc] init];
    self.imgPicker.allowsImageEditing = YES;
    self.imgPicker.delegate = self;
    self.imgPicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.

}

Answer 1

UIPopover是物体的丑陋拼凑而成的野兽。它必须是强大的属性，并且必须是iVar，以确保不会过早达到Dealloc。像这样将其添加到.h中:

@interface MyClass: NSObject {
    UIPopover *_popover;
}
@property (nonatomic, strong) UIPopover * popover;

//.m 

@synthesize popover = _popover;

实例化弹出窗口时，请将其分配给属性或实例:

self.popover = [[UIPopoverController alloc] initWithContentViewController:imgPicker];

要么

_popover = [[UIPopoverController alloc] initWithContentViewController:imgPicker];