使用新的PHPhotoLibrary保存exif元數據

Question

我目前使用AVCaptureStillImageOutput來獲取全分辨率圖片。我還可以使用下面的代碼來獲取EXIF元數據：

[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]; 
    }]; 

元數據位於該mutableDict變量。現在，我想將這張圖片保存在兩個不同的地方，包括元數據。我想將它保存在應用程序文件夾和照片庫中的磁盤上。現在

，我試圖挽救形象，另一種方法，使用下面的（你看到的圖像變量是一個自定義對象）：

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

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

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

現在，圖像被正確保存，但不包含任何Exif元數據。

從我已閱讀的內容中，我需要使用PHPhotoLibrary來做到這一點，但文檔對此不太感興趣。這是我發現的：

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

} completionHandler:nil]; 

但是，如何保存元數據呢？

Answer 1

我會建議你使用的ImageIO來實現這一目標：

-(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 
    }]; 
}