ios – 使用新的PHPhotoLibrary保存exif元数据

2024年1月9日 391次阅读

我目前正在使用AVCaptureStill
ImageOutput来获得完整分辨率的图片.我也可以使用以下代码获取exif元数据：

[self.stillImageOutput captureStillImageAsynchronouslyFromConnection:videoConnection completionHandler: ^(CMSampleBufferRef imageSampleBuffer, NSError *error)
     { 

         CFDictionaryRef metaDict = CMCopyDictionaryOfAttachments(NULL, imageSampleBuffer, kCMAttachmentMode_ShouldPropagate);
         CFMutableDictionaryRef mutableDict = CFDictionaryCreateMutableCopy(NULL, 0, metaDict);

         NSLog(@"test attachments %@", mutableDict);

         // set the dictionary back to the buffer
         CMSetAttachments(imageSampleBuffer, mutableDict, kCMAttachmentMode_ShouldPropagate);

         NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageSampleBuffer];

         UIImage *image = [[UIImage alloc] initWithData:imageData];    
         [self.delegate frameReadyToSave:image withExifAttachments: mutableDict];
     }];

元数据位于mutableDict变量中.现在,我想用两个元数据将这张图片保存在两个不同的地方.我想将它保存在应用程序文件夹和照片库中的磁盘上.

现在,我尝试使用以下方法以另一种方法保存图像(您看到的图像变量是自定义对象)：

NSData* imageData = UIImageJPEGRepresentation(image.image, 1.0f);

[imageData writeToFile:image.filePath atomically:YES];

UIImageWriteToSavedPhotosAlbum(image.image, nil, nil, nil);

现在,图像已正确保存,但不包含任何Exif元数据.

从我读过的内容来看,我需要使用PHPhotoLibrary这样做,但文档并不是那么啰嗦.这是我发现的：

[[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
    PHAssetChangeRequest *createAssetRequest = [PHAssetChangeRequest creationRequestForAssetFromImage:image.image];      

} completionHandler:nil];

但是如何用它保存元数据呢？

最佳答案 我建议您使用ImageIO来实现这一目标：

-(void)frameReadyToSave:(UIImage*)image withExifAttachments:(NSMutableDictionary*)mutableDict
{
    NSData* imageData = UIImageJPEGRepresentation(image, 1.0f);
    CGImageSourceRef source = CGImageSourceCreateWithData((__bridge CFDataRef) imageData, NULL);
    __block NSURL* tmpURL = [NSURL fileURLWithPath:@"example.jpg"]; //modify to your needs
    CGImageDestinationRef destination = CGImageDestinationCreateWithURL((__bridge CFURLRef) tmpURL, kUTTypeJPEG, 1, NULL);
    CGImageDestinationAddImageFromSource(destination, source, 0, (__bridge CFDictionaryRef) mutableDict);
    CGImageDestinationFinalize(destination);
    CFRelease(source);
    CFRelease(destination);
    [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
        [PHAssetChangeRequest creationRequestForAssetFromImageAtFileURL:tmpURL];
    }   completionHandler:^(BOOL success, NSError *error) {
        //cleanup the tmp file after import, if needed
    }];
}
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