如何找出IOS 8上导致didHideZoomSlider错误的原因？

Question

我的应用程序的崩溃日志中出现以下错误

在IOS 8上:

libobjc.A.dylib objc_msgSend + 5 didHideZoomSlider:

Crashed: com.apple.main-thread
EXC_BAD_ACCESS KERN_INVALID_ADDRESS at 0x0000000e 

我不知道从哪里开始？有人知道我应该寻找什么吗？

整个堆栈跟踪:

 0
libobjc.A.dylib     
objc_msgSend + 5 
didHideZoomSlider:
1 Foundation    
__NSFireDelayedPerform + 468
2
CoreFoundation  
__CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 14
3
CoreFoundation  
__CFRunLoopDoTimer + 650
4
CoreFoundation  
__CFRunLoopRun + 1418
5
CoreFoundation  
CFRunLoopRunSpecific + 456
6
    CoreFoundation  
CFRunLoopRunInMode + 106
7
GraphicsServices    
GSEventRunModal + 136
8
UIKit   
UIApplicationMain + 1440
9
main.m line 8
main

错误消息是否表示ImagePickerCameraView出现问题？

我有时也会得到

 Crashed: com.apple.main-thread
 EXC_BAD_ACCESS KERN_INVALID_ADDRESS at 0xeec1ff5e
 0 libobjc.A.dylib  objc_msgSend + 21 didHideZoomSlider:

如果ImagePicker是麻烦制造者,这里是一段代码摘录:

- (IBAction)onTakePictureToolbarButtonPushed:(id)sender {
    UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
    [imagePicker setSourceType:
        [UIImagePickerController  isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]
            ? UIImagePickerControllerSourceTypeCamera
            : UIImagePickerControllerSourceTypePhotoLibrary
    ];

    [imagePicker setDelegate:self];
    [self presentViewController:imagePicker animated:YES completion:nil];
}



- (void)imagePickerController: (UIImagePickerController *)picker didFinishPickingMediaWithInfo: (NSDictionary *)info {
UIImage* rawImage = [info objectForKey: UIImagePickerControllerOriginalImage];

NSData *imageData = UIImageJPEGRepresentation(rawImage, 0.3);
[imageData writeToFile: @"img.jpg" atomically: YES];

[self dismissViewControllerAnimated: YES completion:nil];
[self.tableView reloadData];

}

Answer 1

我已经能够在我的代码中复制这个问题了.这似乎是Apple代码中的一个错误,是一个时间问题.

我没有通过点击实际拍摄照片来复制它,但是当我点击取消时我可以复制它.您可以尝试在代码中执行此操作,并查看它是否适合您.打开相机拍照,然后捏缩放.您将在屏幕上显示一个小缩放滑块.大约4-5秒后,变焦幻灯片逐渐消失.这是时间进入的地方.如果你点击取消就开始褪色,你可以让它崩溃.

我的假设是Apple有一个动画块,它会缩小缩放滑块.在完成该动画时,它调用它didHideZoomSlider:而不检查它对图像选择器的引用.

我认为在我的取消代码上复制更容易,因为它非常简单:

- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker {
    [self dismissViewControllerAnimated:YES completion:nil];
}

我的假设是,由于执行得如此之快,因此可以在该动画的中间将其解除.因此,我的解决方案是在很短的时间内实际推迟我对视图的解雇.

- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker {
    __weak typeof(self) wSelf = self;
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.1 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        [wSelf dismissViewControllerAnimated:YES completion:nil];
    });
}

我不认为这会"修复"这个问题,但会减少它,以至于我再也无法复制它了.这应该是Apple的错误(我接下来会做).

更新:发送给Apple.

Answer 2

添加延迟我没有太多运气.崩溃仍然发生在我的情况下(iOS 8和9.0.1).

有一个OpenRadar建议删除CAMZoomSlider可能导致崩溃的代表,这对我来说效果很好.

但是,用户要小心,因为这会操纵私有类,并可能导致App Store提交拒绝...

要修复委托,子类的问题UIImagePickerController并添加以下内容:

- (void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];
    [self clearZoomSliderDelegateForClass:[self sliderClass] subviews:self.view.subviews];
}

- (void)clearZoomSliderDelegateForClass:(Class)sliderClass subviews:(NSArray *)subviews {
    for (UIView *subview in subviews) {
        if ([subview isKindOfClass:sliderClass] && [subview respondsToSelector:@selector(setDelegate:)]) {
            [subview performSelector:@selector(setDelegate:) withObject:nil];
            return;
        }
        else {
            [self clearZoomSliderDelegateForClass:sliderClass subviews:subview.subviews];
        }
    }
}

- (Class)sliderClass {
    for (NSString* prefix in @[@"CAM", @"CMK"]) {
        Class zoomClass = NSClassFromString([prefix stringByAppendingString:@"ZoomSlider"]);
        if (zoomClass != Nil) {
            return zoomClass;
        }
    }
    return Nil;
}

在iOS 9 SDK中,私有CameraKit框架前缀从更改CAM为CMK(只需使用可视调试器检查滑块),因此必须更新以前的解决方法.

此崩溃在日志中也可能如下所示:

0   libobjc.A.dylib                      0x3591fae6 objc_msgSend + 6
1   Foundation                           0x24d28e59 __NSFireDelayedPerform + 466
...