UIImagePickerController错误:在iOS 7中快照未呈现的视图会导致空快照

Question

我只在iOS 7中收到此错误并且应用程序崩溃了.在iOS 6中,我从未收到任何错误,只是在打开相机时出现内存警告.

Snapshotting a view that has not been rendered results in an empty snapshot. Ensure your view has been rendered at least once before snapshotting or snapshot after screen updates.

这就是我在做的事情.

imagePicker = [[UIImagePickerController alloc] init];
[imagePicker setDelegate:self];
[imagePicker setSourceType:UIImagePickerControllerSourceTypeCamera];
[imagePicker setAllowsEditing:YES];

[self presentModalViewController:imagePicker animated:YES];

我确实试图延迟presentModalViewController,但我仍然得到相同的消息.几秒钟后(7-10),应用程序崩溃了.

此错误仅出现在iOS 7中.

有人有线索吗？先感谢您.

Answer 1

iOS7中的问题与转换有关.似乎如果之前的转换没有完成并且您启动了一个新转换,iOS7会混淆视图,其中iOS6似乎正确地管理它.

UIViewController只有在视图已加载且超时后,才应在您的相机中初始化相机:

- (void)viewDidAppear:(BOOL)animated 
{
    [super viewDidAppear:animated];
    //show camera...
    if (!hasLoadedCamera)
        [self performSelector:@selector(showcamera) withObject:nil afterDelay:0.3];
}

这是初始化代码

- (void)showcamera {
    imagePicker = [[UIImagePickerController alloc] init];
    [imagePicker setDelegate:self];
    [imagePicker setSourceType:UIImagePickerControllerSourceTypeCamera];
    [imagePicker setAllowsEditing:YES];

    [self presentModalViewController:imagePicker animated:YES];
}

Answer 2

Apple的PhotoPicker示例代码项目也出现了这个错误.

我在iPhone 4上使用Xcode Version 5.0和iOS 7.0.3.

重现步骤:

1. 通过https://developer.apple.com/library/ios/samplecode/PhotoPicker/Introduction/Intro.html下载Apple的PhotoPicker示例项目

2. 在APLViewController.m中注释掉第125行

   //imagePickerController.showsCameraControls = NO;

3. 在APLViewController.m中注释掉第130-133行

   //[[NSBundle mainBundle] loadNibNamed:@"OverlayView" owner:self options:nil];
// self.overlayView.frame = imagePickerController.cameraOverlayView.frame;
// imagePickerController.cameraOverlayView = self.overlayView;
// self.overlayView = nil;

4. 构建并启动应用程序.

5. 启动后,将设备旋转到横向模式.

6. 单击"相机"图标以在"相机"模式下打开UIImagePickerController.

7. 查看控制台输出.

控制台输出

PhotoPicker [240:60b]快照未渲染的视图会导致空快照.确保在屏幕更新后快照或快照之前至少渲染了一次视图.

showsCameraControls属性

当它的值为YES(默认值)时,会出现问题.

将此设置为NO会消除该消息.

错误报告

我刚刚向Apple提交了一份错误报告.

我尝试了很多在不同帖子中提出的建议,但没有找到令人满意的解决方法.

Answer 3

当我试图在弹出窗口中显示摄像机视图时,我遇到了问题.在iOS6下这没问题,但在iOS7中我得到了消息

Snapshotting a view that has not been rendered results in an empty snapshot. Ensure your view has been rendered at least once before snapshotting or snapshot after screen updates.

同样.

然而,在我将相机视图的显示更改为全屏后,如拍摄照片和电影中所述,iOS开发者库一切都恢复正常,消息再也没有出现.但是我必须确保取决于应用程序在哪种模式下(即,呈现相机视图或照片滚动),我必须- (void) imagePickerControllerDidCancel: (UIImagePickerController *) picker在调用方法时关闭弹出窗口或视图控制器.

Answer 4

创建一个属性

@property (nonatomic) UIImagePickerController *imagePickerController;

然后

UIImagePickerController *picker = [[UIImagePickerController alloc] init];
picker.delegate = self;
picker.modalPresentationStyle = UIModalPresentationCurrentContext;
picker.sourceType = UIImagePickerControllerSourceTypeCamera;
picker.allowsEditing = YES;
self.imagePickerController = picker;
[self presentViewController:self.imagePickerController animated:YES completion:nil];

这应该可以解决问题