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keepMeta is not working on iOS

See original GitHub issue

I want to keep metadata when resizing an image. I used ImageResizer.createResizedImage with keepMeta = true. However, it is not working on iOS.

As a result of the analysis, getImageMeta() function is not working. It returns before getting the metadata from an image URI.

NSMutableDictionary * getImageMeta(NSString * path)
{
    if([path hasPrefix:@"assets-library"]) {

        __block NSMutableDictionary* res = nil;

        ALAssetsLibraryAssetForURLResultBlock resultblock = ^(ALAsset *myasset)
        {
           // (1) here asynchronous processing
            NSDictionary *exif = [[myasset defaultRepresentation] metadata];
            res = [exif mutableCopy];

        };

        ALAssetsLibrary* assetslibrary = [[ALAssetsLibrary alloc] init];
        NSURL *url = [NSURL URLWithString:[path stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];

        [assetslibrary assetForURL:url resultBlock:resultblock failureBlock:^(NSError *error) { NSLog(@"error couldn't image from assets library"); }];

       // (2) result is returned before (1) is finished.
        return res;

    }

this issue can be prevented by using semaphore system.

environment

iPhoneSE 2generation (IOS 14.81) / iPhone12ProMax (iOS 15.1) react-native: 0.63.4 react-native-image-resizer: 1.4.5

Issue Analytics

State:
Created 2 years ago
Comments:6 (1 by maintainers)

Top GitHub Comments

2reactions

ishikawa-takumicommented, Feb 23, 2022

@odexvy Yes, I have prevented this issue applying the following code. node_modules/react-native-image-resizer/ios/RCTImageResizer.m

NSMutableDictionary * getImageMeta(NSString * path)
{
    if([path hasPrefix:@"assets-library"] ) {

        __block NSMutableDictionary* res = nil;
        dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);  
        @try {
            dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^{
                ALAssetsLibraryAssetForURLResultBlock resultblock = ^(ALAsset *myasset)
                {

                    NSDictionary *exif = [[myasset defaultRepresentation] metadata];
                    res = [exif mutableCopy];
                    dispatch_semaphore_signal(semaphore);

                };

                ALAssetsLibrary* assetslibrary = [[ALAssetsLibrary alloc] init];
                NSURL *url = [NSURL URLWithString:[path stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];

                [assetslibrary assetForURL:url resultBlock:resultblock failureBlock:^(NSError *error) { NSLog(@"error couldn't image from assets library"); }];
            });
        } 
        @finally {
            dispatch_time_t time = dispatch_time(DISPATCH_TIME_NOW, 3 * NSEC_PER_SEC);
            dispatch_semaphore_wait(semaphore, time);
            return res;
        }
    } else {

1reaction

odexvycommented, Feb 23, 2022

thank you very much @ishikawa-takumi 👍