iOS 8 PhotoKit. Get maximum-size image from iCloud Photo Sharing albums

问题

How get access to the full-size images from iСloud? Every time I try to get this picture, I get image size 256x342. I not see progress too.

Code:

    PHFetchResult *result = [PHAsset fetchAssetsWithLocalIdentifiers:@[assetIdentifier] options:nil];
    PHImageManager *manager = [PHImageManager defaultManager];
    [result enumerateObjectsUsingBlock:^(PHAsset *asset, NSUInteger idx, BOOL *stop) {

        PHImageRequestOptions *options = [[PHImageRequestOptions alloc] init];
        options.deliveryMode = PHImageRequestOptionsDeliveryModeHighQualityFormat;
        options.synchronous = YES;
        options.networkAccessAllowed = YES;
        options.progressHandler = ^(double progress, NSError *error, BOOL *stop, NSDictionary *info) {
            NSLog(@"%f", progress);
        };

        [manager requestImageForAsset:asset targetSize:PHImageManagerMaximumSize contentMode:PHImageContentModeDefault options:options resultHandler:^(UIImage *resultImage, NSDictionary *info)
         {
             UIImage *image = resultImage;
             NSLog(@"%@", NSStringFromCGSize(resultImage.size));
         }];
    }];

Until I click the picture in Photo app, this picture will be of poor quality. But as soon as I click on the picture, it downloaded on the device and will be full-size quality.

回答1:

I think the below should get the full resolution image data:

 [manager requestImageDataForAsset:asset 
                           options:options 
                     resultHandler:^(NSData *imageData, NSString *dataUTI, UIImageOrientation orientation, NSDictionary *info) 
             { 
                  UIImage *image = [UIImage imageWithData:imageData]; 

                  //...

             }];

The entire Photos Framework (PhotoKit) is covered in the WWDC video: https://developer.apple.com/videos/wwdc/2014/#511

Hope this helps.

Edit:

The resultHandler can be called twice. This is explained in the video I linked to at around 30:00. Could be that you are only getting the thumbnail and the full image will come with the second time its called.

回答2:

I'm having some of the same issues. It is either a bug or poor documentation. I've been able to get around the issue by specifying a requested size of 2000x2000. The problem with this is that I do get the full size image but sometimes it comes back marked as degraded so I keep waiting for a different image which never happens. This is what I do to get around those issues.

        self.selectedAsset = asset;

        self.collectionView.allowsSelection = NO;

        PHImageRequestOptions* options = [[[PHImageRequestOptions alloc] init] autorelease];
        options.synchronous = NO;
        options.version = PHImageRequestOptionsVersionCurrent;
        options.deliveryMode = PHImageRequestOptionsDeliveryModeOpportunistic;
        options.resizeMode = PHImageRequestOptionsResizeModeNone;
        options.networkAccessAllowed = YES;
        options.progressHandler =  ^(double progress,NSError *error,BOOL* stop, NSDictionary* dict) {
            NSLog(@"progress %lf",progress);  //never gets called
        };

        [self.delegate choosePhotoCollectionVCIsGettingPhoto:YES];  //show activity indicator
        __block BOOL isStillLookingForPhoto = YES;

        currentImageRequestId = [[PHImageManager defaultManager] requestImageForAsset:asset targetSize:CGSizeMake(2000, 2000) contentMode:PHImageContentModeAspectFill options:options resultHandler:^(UIImage *result, NSDictionary *info) {
            NSLog(@"result size:%@",NSStringFromCGSize(result.size));

            BOOL isRealDealForSure = NO;
            NSNumber* n = info[@"PHImageResultIsPlaceholderKey"]; //undocumented key so I don't count on it
            if (n != nil && [n boolValue] == NO){
                isRealDealForSure = YES;
            }

            if([info[PHImageResultIsInCloudKey] boolValue]){
                NSLog(@"image is in the cloud"); //never seen this. (because I allowed network access)
            }
            else if([info[PHImageResultIsDegradedKey] boolValue] && !isRealDealForSure){
                    //do something with the small image...but keep waiting
                [self.delegate choosePhotoCollectionVCPreviewSmallPhoto:result];
                self.collectionView.allowsSelection = YES;
                dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(3.0 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{ //random time of 3 seconds to get the full resolution in case the degraded key is lying to me. The user can move on but we will keep waiting.
                    if(isStillLookingForPhoto){
                        self.selectedImage = result;
                        [self.delegate choosePhotoCollectionVCPreviewFullPhoto:self.selectedImage]; //remove activity indicator and let the user move on
                    }
                });
            }
            else {
                    //do something with the full result and get rid of activity indicator.
                if(asset == self.selectedAsset){
                    isStillLookingForPhoto = NO;
                    self.selectedImage = result;
                    [self.delegate choosePhotoCollectionVCPreviewFullPhoto:self.selectedImage];
                    self.collectionView.allowsSelection = YES;
                }
                else {
                    NSLog(@"ignored asset because another was pressed");
                }
            }
        }];

回答3:

To get the full size image you need to check the info list. I used this to test if the returned result is the full image, or a degraded version.

if ([[info valueForKey:@"PHImageResultIsDegradedKey"]integerValue]==0){
    // Do something with the FULL SIZED image
} else {
    // Do something with the regraded image
}

or you could use this to check if you got back what you asked for.

if ([[info valueForKey:@"PHImageResultWantedImageFormatKey"]integerValue]==[[info valueForKey:@"PHImageResultDeliveredImageFormatKey"]integerValue]){
    // Do something with the FULL SIZED image
} else {
    // Do something with the regraded image
}

There are a number of other, undocumented but useful, keys e.g.

PHImageFileOrientationKey = 3;
PHImageFileSandboxExtensionTokenKey = "/private/var/mobile/Media/DCIM/100APPLE/IMG_0780.JPG";
PHImageFileURLKey = "file:///var/mobile/Media/DCIM/100APPLE/IMG_0780.JPG";
PHImageFileUTIKey = "public.jpeg";
PHImageResultDeliveredImageFormatKey = 9999;
PHImageResultIsDegradedKey = 0;
PHImageResultIsInCloudKey = 0;
PHImageResultIsPlaceholderKey = 0;
PHImageResultRequestIDKey = 1;
PHImageResultWantedImageFormatKey = 9999;

Have fun. Linasses

回答4:

I believe it's related to you setting PHImageRequestOptionsDeliveryModeOpportunistic. Note that this is not even supported for asynchronous mode (default). Try PHImageRequestOptionsDeliveryModeHighQualityFormat intead.

来源：https://stackoverflow.com/questions/25841795/ios-8-photokit-get-maximum-size-image-from-icloud-photo-sharing-albums