从UIImagePickerControlleHow的结果来看，如何获得包含元数据的JPEG？
在iOS 4.2上，当我使用UIImagePickerController让用户从照片库中选择一个图像时，这些是返回给我的字典键：
2011-03-02 13:15:59.518 xxx[15098:307] didFinishPickingMediaWithInfo:
info dictionary: {
UIImagePickerControllerMediaType = "public.image";
UIImagePickerControllerOriginalImage = "<UIImage: 0x3405d0>";
UIImagePickerControllerReferenceURL =
"assets-library://asset/asset.JPG?id=1000000050&ext=JPG";
}
没有找到相关结果
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1 个回复
届甸衬丝蚕
ala：这似乎没有给你（大部分）图像中的元数据（EXIF，GPS等）。很公平，我认为这是众所周知的。 我的测试表明，图像资产的“默认表示”中的JPEG将包含所有元数据，包括EXIF和GPS信息（假设它首先出现在那里）。您可以通过从资产URL到资产到资产的默认表示（ALAssetRepresentation）然后使用getBytes方法/消息来检索JPEG图像的字节来获取该图像。该字节流具有上述元数据。 这是我用于此的一些示例代码。它需要一个资产URL，假设是一个图像，并返回带有JPEG的NSData。注意你的使用，代码中的错误处理等。/* * Example invocation assuming that info is the dictionary returned by * didFinishPickingMediaWithInfo (see original SO question where * UIImagePickerControllerReferenceURL = "assets-library://asset/asset.JPG?id=1000000050&ext=JPG"). */ [self getJPEGFromAssetForURL:[info objectForKey:UIImagePickerControllerReferenceURL]]; // ... /* * Take Asset URL and set imageJPEG property to NSData containing the * associated JPEG, including the metadata we're after. */ -(void)getJPEGFromAssetForURL:(NSURL *)url { ALAssetsLibrary* assetslibrary = [[ALAssetsLibrary alloc] init]; [assetslibrary assetForURL:url resultBlock: ^(ALAsset *myasset) { ALAssetRepresentation *rep = [myasset defaultRepresentation]; #if DEBUG NSLog(@"getJPEGFromAssetForURL: default asset representation for %@: uti: %@ size: %lld url: %@ orientation: %d scale: %f metadata: %@", url, [rep UTI], [rep size], [rep url], [rep orientation], [rep scale], [rep metadata]); #endif Byte *buf = malloc([rep size]); // will be freed automatically when associated NSData is deallocated NSError *err = nil; NSUInteger bytes = [rep getBytes:buf fromOffset:0LL length:[rep size] error:&err]; if (err || bytes == 0) { // Are err and bytes == 0 redundant? Doc says 0 return means // error occurred which presumably means NSError is returned. NSLog(@"error from getBytes: %@", err); self.imageJPEG = nil; return; } self.imageJPEG = [NSData dataWithBytesNoCopy:buf length:[rep size] freeWhenDone:YES]; // YES means free malloc'ed buf that backs this when deallocated } failureBlock: ^(NSError *err) { NSLog(@"can't get asset %@: %@", url, err); }]; [assetslibrary release]; }