问题
My app crashes every time when I try to save image using photo framework.
-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{
_mChangeRequest = [PHAssetChangeRequest creationRequestForAssetFromImage:[info valueForKey:UIImagePickerControllerOriginalImage]];
[[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
_mChangeRequest = [PHAssetChangeRequest creationRequestForAssetFromImage:[info valueForKey:UIImagePickerControllerOriginalImage]];
} completionHandler:^(BOOL success, NSError *error) {
if (success) {
PHObjectPlaceholder *assetPlaceholder = _mChangeRequest.placeholderForCreatedAsset;
}
else {
NSLog(@"write error : %@",error);
}
}];
}
crash : NSInternalInconsistencyException', reason: 'This method can only be called from inside of -[PHPhotoLibrary performChanges:completionHandler:] or -[PHPhotoLibrary performChangesAndWait:error:]'
回答1:
All you need to do is trigger a creation request. As the error says, you can access the change request only inside the performChanges block.
So to save the image you would do something like this:
[[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
[PHAssetChangeRequest creationRequestForAssetFromImage:[info valueForKey:UIImagePickerControllerOriginalImage]];
} completionHandler:^(BOOL success, NSError *error) {
if (success) {
NSLog(@"Success");
}
else {
NSLog(@"write error : %@",error);
}
}];
In case you need to do something with the placeholder of the newly created asset, you can access it inside the same performChanges block:
PHAssetChangeRequest *changeRequest = [PHAssetChangeRequest creationRequestForAssetFromImage:[info valueForKey:UIImagePickerControllerOriginalImage]];
PHObjectPlaceholder *assetPlaceholder = changeRequest.placeholderForCreatedAsset;
回答2:
In Swift 3 I do this to save the video to the library.
if mediaType.isEqual(to: (kUTTypeMovie as NSString) as String) {
if let videoURL = info[UIImagePickerControllerMediaURL] as? URL {
PHPhotoLibrary.shared().performChanges({
_ = PHAssetChangeRequest.creationRequestForAssetFromVideo(atFileURL: videoURL)
}, completionHandler: { (success, error) in
if success {
print("ok")
let videoData = NSData(contentsOf: videoURL)
// use videoData here if needed...
if let posterImage = self.firstFrame(videoURL: videoURL) {
self.imageView.image = posterImage
}
picker.dismiss(animated: true) { () -> Void in
}
}
else {
print(error?.localizedDescription)
}
})
}
}
回答3:
Here is an example of code how you can write/save image to Photo Library using UIImageWriteToSavedPhotosAlbum function:
- (void)saveImage:(UIImage *)image {
UIImageWriteToSavedPhotosAlbum(self.image, self, @selector(image:didFinishSavingWithError:contextInfo:), NULL);
}
- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo;
{
if (!error) {
// saved successfully
PHFetchOptions *fetchOptions = [PHFetchOptions new];
fetchOptions.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@"creationDate" ascending:NO]];
PHAsset *asset = [PHAsset fetchAssetsWithMediaType:PHAssetMediaTypeImage options:fetchOptions].firstObject;
if (asset != nil) {
// here you can use asset of your image
}
} else {
NSLog(@"save image error: %@", error);
}
}
Don't forget to add into your Info.plist a key-value pair Privacy - Camera Usage Description with description of usage.
回答4:
- delete third line of the code
- Verify that the _mChangeRequest is __block variable
- compile and run
you will see that image in the photos app
you will change code probably like this...
-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{
__block PHAssetChangeRequest *_mChangeRequest = nil;
[[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
_mChangeRequest = [PHAssetChangeRequest creationRequestForAssetFromImage:[info valueForKey:UIImagePickerControllerOriginalImage]];
} completionHandler:^(BOOL success, NSError *error) {
if (success) {
PHObjectPlaceholder *assetPlaceholder = _mChangeRequest.placeholderForCreatedAsset;
}
else {
NSLog(@"write error : %@",error);
}
}];
}
来源：https://stackoverflow.com/questions/31693375/save-image-to-photo-library-using-photo-framework