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

我使用Phonegap,但这个线程一直作为第一个当谷歌关于错误消息。

对我来说,通过将imagetype定义为PNG,这个问题就消失了。

encodingType : Camera.EncodingType.PNG

所以整条线是:

 navigator.camera.getPicture(successFunction, failFunction, { encodingType : Camera.EncodingType.PNG, correctOrientation:true, sourceType : Camera.PictureSourceType    .PHOTOLIBRARY, quality: 70, allowEdit : false , destinationType: Camera.DestinationType.DATA_URL});

你的里程可能会有所不同,但这对我来说很管用。

其他回答

我遇到过这个问题。当我们调用相机并释放视图时就产生了这个问题。举个例子,调用一个相机并在viewDidDisappear方法中设置视图为nil,这个错误将会出现,因为没有相机事件的回调。对于这个错误,也要确认一下。

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];
    });
}

在我的情况下(XCode 7和iOS 9),我使用UINavigationController“隐藏”,所以我必须添加UINavigationControllerDelegate来呈现相机或滚动,它的工作就像它应该做的!和pickerControllerDelegate。Self也不显示错误!

或者,考虑使用drawviewherarchyinrect:

迅速:

extension UIImage{

    class func renderUIViewToImage(viewToBeRendered: UIView) -> UIImage
    {
        UIGraphicsBeginImageContextWithOptions(viewToBeRendered.bounds.size, true, 0.0)
        viewToBeRendered.drawViewHierarchyInRect(viewToBeRendered.bounds, afterScreenUpdates: true)
        viewToBeRendered.layer.renderInContext(UIGraphicsGetCurrentContext()!)

        let finalImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        return finalImage
    }
}

objective - c:

- (UIImage *)snapshot:(UIView *)view
{
    UIGraphicsBeginImageContextWithOptions(view.bounds.size, YES, 0);
    [view drawViewHierarchyInRect:view.bounds afterScreenUpdates:YES];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return image;
}

还看到:

https://developer.apple.com/library/ios/qa/qa1817/_index.html 如何捕获UIView到UIImage而不损失视网膜显示的质量

这可能是内置ImagePickerController的错误。我的代码可以运行,但在iPhone 6 Plus上偶尔会崩溃。

我已经尝试了其他答案提出的所有解决方案,但都没有运气。问题最终解决后切换到JPSImagePickerController。