在iOS 8中,我有从相机捕捉图像的问题,直到现在我正在使用这段代码

UIImagePickerController *controller=[[UIImagePickerController alloc] init];
controller.videoQuality=UIImagePickerControllerQualityTypeMedium;
controller.delegate=(id)self;
controller.sourceType=UIImagePickerControllerSourceTypeCamera;
[self presentViewController:controller animated:YES completion:nil];

但在iOS 8中,我得到了这个:

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.

我已经尝试了本文提供的解决方案

@property (strong,nonatomic)UIImagePickerController *controller;

_controller=[[UIImagePickerController alloc] init];
_controller.videoQuality=UIImagePickerControllerQualityTypeMedium;
_controller.delegate=(id)self;
_controller.sourceType=UIImagePickerControllerSourceTypeCamera;
_[self presentViewController:controller animated:YES completion:nil];

...
controller.modalPresentationStyle=UIModalPresentationFullScreen;
or
controller.modalPresentationStyle=UIModalPresentationCurrentContext;
...

double delayInSeconds = 0.1;
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
    [self presentViewController:controller animated:YES completion:nil];
});

[self presentViewController:controller animated:YES completion:NULL];

[self presentViewController:controller animated:YES completion:^{

}];

任何想法?


当前回答

我也遇到了同样的问题,我通过检查相机是否可用来解决它:

BOOL cameraAvailableFlag = [UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera];
    if (cameraAvailableFlag)
        [self performSelector:@selector(showcamera) withObject:nil afterDelay:0.3];

其他回答

我已经尝试了一切,我的问题是,相机和图片库的图像选择器在它们显示后立即消失。我用下面这行(swift)解决了它

imagePicker.modalPresentationStyle = UIModalPresentationStyle.OverCurrentContext

I don't have enough reputation points to comment on @greg's answer above, so will add my observations here. I have a Swift project for both iPad and iPhone. I have a method inside my main view controller (relevant bit below). When I test this on a phone, everything works properly and no warnings are generated. When I run it on an iPad, everything works properly but I see the warning about snapshotting the view. The interesting bit, however, is that when I run on an iPad without using the popover controller, everything works properly with no warning. Unfortunately, Apple mandates that the image picker must be used within a popover on iPad, if the camera is not being used.

    dispatch_async(dispatch_get_main_queue(), {
        let imagePicker: UIImagePickerController = UIImagePickerController();
        imagePicker.sourceType = UIImagePickerControllerSourceType.SavedPhotosAlbum;
        imagePicker.mediaTypes = [kUTTypeImage];
        imagePicker.allowsEditing = false;
        imagePicker.delegate = self;

        if(UIDevice.currentDevice().userInterfaceIdiom == .Pad){ // on a tablet, the image picker is supposed to be in a popover
            let popRect: CGRect = buttonRect;
            let popover: UIPopoverController = UIPopoverController(contentViewController: imagePicker);
            popover.presentPopoverFromRect(popRect, inView: self.view, permittedArrowDirections: UIPopoverArrowDirection.Up, animated: true);
        }else{
            self.presentViewController(imagePicker, animated: true, completion: nil);
        }
    });

我在调用UIImagePickerController presentViewController后遇到了这个:从回调到UIAlertView委托。我通过推presentViewController解决了这个问题:使用dispatch_async调用当前执行跟踪。

- (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex
{
    dispatch_async(dispatch_get_main_queue(), ^{
        UIImagePickerController *imagePickerController = [[UIImagePickerController alloc] init];
        imagePickerController.delegate = self;

        if (buttonIndex == 1)
            imagePickerController.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
        else
            imagePickerController.sourceType = UIImagePickerControllerSourceTypeCamera;

        [self presentViewController: imagePickerController
                           animated: YES
                         completion: nil];
    });
}

我得到了同样的错误,在控制台怒吼的消息,同时打开相机。

’对一个没有被渲染的视图进行快照会导致一个空快照。确保你的视图在快照之前或屏幕更新后至少渲染过一次。”

对我来说,问题是在信息中的捆绑显示名称。plist文件。它是空的某种方式,我把我的应用程序名称在那里,现在它工作正常。我没有收到任何相机权限警报,因为空的Bundle显示名称。它阻止了视图的呈现。

问题不在于视图,而在于未经许可而呈现视图。你可以检查设置>隐私>相机,如果你的应用程序没有列出,问题可能是一样的。

如果我们使用UIImagePickerController作为属性,那么这个警告将会消失。xcode假设我们没有使用UIImagePickerController的结果,如果我们在一个函数中实例化UIImagePickerController。