利用ImageIo读取图片的元数据

- (void)readXMPForImageWithURL:(NSURL *)url 

{ 

  CGImageSourceRef imageSourceRef = CGImageSourceCreateWithURL((__bridge CFURLRef)url, NULL);                 CGImageMetadataRef metadataRef = CGImageSourceCopyMetadataAtIndex(imageSourceRef, 0, NULL);

  if (NULL == metadataRef) { return; } 

  NSLog(@"metadata = \n%@", metadataRef);

 }

- (void)readXMPForImageWithData:(NSData *)data

{ 

   CGImageSourceRef imageSourceRef = CGImageSourceCreateWithData((__bridge CFDataRef)data, NULL);       

   CGImageMetadataRef metadataRef = CGImageSourceCopyMetadataAtIndex(imageSourceRef, 0, NULL);

   if (NULL == metadataRef) {  return; } 

   NSLog(@"metadata = \n%@", metadataRef);

 }