如何在不更改图像的情况下更新ALAsset的exif? [英] How to update exif of ALAsset without changing the image?

问题描述

我使用ALAsset的setImageData:metadata:completionBlock:来更新资产的exif(元数据).

I use setImageData:metadata:completionBlock: of ALAsset to update the exif(metadata) of an asset.

我只想更新元数据，但是此方法需要imageData作为第一个参数.我使用下面的代码生成imageData，但是它修改了我的图片(我检查了文件大小和文件哈希).

I just want to update the metadata, but this method require an imageData as the first parameter. I use the code below to generate imageData, but it modified my image(I checked the file size and file hash).

ALAssetRepresentation *dr = asset.defaultRepresentation;
UIImage *image = [UIImage imageWithCGImage:dr.fullResolutionImage scale:dr.scale orientation:dr.orientation];
NSData *data = UIImageJPEGRepresentation(image, 1);

还有其他方法可以用来更新ALAsset的exif吗?或为方法setImageData:metadata:completionBlock:生成正确的imageData的任何方法?

Is there any other method I could use to update just the exif of an ALAsset? Or any way to generate the right imageData for method setImageData:metadata:completionBlock: ?

推荐答案

我找到了一种生成imageData的方法.下面的代码:

I found a way to generate imageData. Code below:

Byte *buffer = (Byte *)malloc(dr.size);
NSUInteger k = [dr getBytes:buffer fromOffset:0.0 length:dr.size error:nil];
NSData *data = [NSData dataWithBytesNoCopy:buffer length:k freeWhenDone:YES];

所以我可以将上面的数据与setImageData:metadata:completionBlock:一起使用，以仅更新ALAsset的exif.

So I can use the data above with setImageData:metadata:completionBlock: to update only the exif of ALAsset.

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