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];
这
...
controller.modalPresentationStyle=UIModalPresentationFullScreen;
or
controller.modalPresentationStyle=UIModalPresentationCurrentContext;
...
这
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];
});
这
[self presentViewController:controller animated:YES completion:NULL];
这
[self presentViewController:controller animated:YES completion:^{
}];
任何想法?
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
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);
}
});
