UIPopoverController 的奇怪错误

Question

我正在尝试使用 UIImagePickerController 从用户 iPhone / iPad 上的照片中抓取照片。这段代码在 iPhone 上运行得很好，但是当我在 iPad 上运行它时，调试器给了我消息“由于未捕获的异常 'NSGenericException' 导致应用程序终止，原因：'-[UIPopoverController dealloc] 在弹出窗口仍然可见时达到。”。我对 Objective-C 很陌生，所以我不确定是什么原因造成的，我没有释放任何东西，我打开了 ARC。这是我的代码： 视图控制器.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 是一个丑陋的拼凑对象。它必须是一个强大的属性和一个 iVar，以确保不会过早地达到 Dealloc。在 .h 中添加这个像这样：

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

//.m 

@synthesize popover = _popover;

实例化弹出框时，将其分配给属性或实例：

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

或

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