EXIF数据不与图像一起保存?

Question

我想在特定相册中保存一些带有图像的字符串。 所以我用了[[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{以添加资产。

但是当我从相册中获取照片时，它没有EXIF数据。

我保存EXIF数据的代码在这里。请回答。

- (void)addImageToCameraRoll:(UIImage *)image didfinish:(NSString *)albumName {
void (^saveBlock)(PHAssetCollection *assetCollection) = ^void(PHAssetCollection *assetCollection) {
NSData* jpeg = UIImageJPEGRepresentation(image, 1.0f);
CGImageSourceRef source = CGImageSourceCreateWithData((__bridge CFDataRef) jpeg, NULL);
CFStringRef imageType = CGImageSourceGetType(source);
NSDictionary *metadata = (NSDictionary *) CFBridgingRelease(CGImageSourceCopyPropertiesAtIndex(source, 0, NULL));
NSMutableDictionary *metadataAsMutable = [metadata mutableCopy];
NSMutableDictionary *EXIFDictionary = [[metadataAsMutable objectForKey:(NSString *)kCGImagePropertyExifDictionary]mutableCopy];
NSMutableDictionary *GPSDictionary = [[metadataAsMutable objectForKey:(NSString *)kCGImagePropertyGPSDictionary]mutableCopy];
if(!EXIFDictionary){
//if the image does not have an EXIF dictionary (not all images do), then create one for us to use
EXIFDictionary = [NSMutableDictionary dictionary];
}
if(!GPSDictionary){
GPSDictionary = [NSMutableDictionary dictionary];
}
[GPSDictionary setValue:[NSNumber numberWithFloat:1.1] forKey:(NSString*)kCGImagePropertyGPSLatitude];
[GPSDictionary setValue:[NSNumber numberWithFloat:2.2] forKey:(NSString*)kCGImagePropertyGPSLongitude];
[EXIFDictionary setValue:@"my string to exif" forKey:(NSString *)kCGImagePropertyExifUserComment];
[metadataAsMutable setObject:EXIFDictionary forKey:(NSString *)kCGImagePropertyExifDictionary];
[metadataAsMutable setObject:GPSDictionary forKey:(NSString *)kCGImagePropertyGPSDictionary];
NSMutableData *resultData = [NSMutableData data];
CGImageDestinationRef imgDest = CGImageDestinationCreateWithData((__bridge CFMutableDataRef)(resultData), imageType, 1, NULL);
//copy image data
CGImageDestinationAddImageFromSource(imgDest, source, 0, (CFDictionaryRef) metadataAsMutable);
BOOL success = CGImageDestinationFinalize(imgDest);
UIImage * image1 = [[UIImage alloc] initWithData:resultData];

//Add assets
[[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
PHAssetChangeRequest *assetChangeRequest = [PHAssetChangeRequest creationRequestForAssetFromImage:image1];

PHObjectPlaceholder *assetPlaceholder = assetChangeRequest.placeholderForCreatedAsset;
PHAssetCollectionChangeRequest *albumChangeRequest =
[PHAssetCollectionChangeRequest changeRequestForAssetCollection:assetCollection];
[albumChangeRequest addAssets:@[ assetPlaceholder ]];
}
completionHandler:^(BOOL success, NSError *error) {
if (!success) {
NSLog(@"Error creating asset: %@", error);
}else{
}
}];
};

PHFetchOptions *fetchOptions = [[PHFetchOptions alloc] init];
fetchOptions.predicate = [NSPredicate predicateWithFormat:@"localizedTitle = %@", albumName];
PHFetchResult *fetchResult = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeAny options:fetchOptions];
if (fetchResult.count > 0) {
saveBlock(fetchResult.firstObject);
}
else {
__block PHObjectPlaceholder *albumPlaceholder;
[[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
PHAssetCollectionChangeRequest *changeRequest = [PHAssetCollectionChangeRequest creationRequestForAssetCollectionWithTitle:albumName];
albumPlaceholder = changeRequest.placeholderForCreatedAssetCollection;
} completionHandler:^(BOOL success, NSError *error) {
if (success) {
PHFetchResult *fetchResult = [PHAssetCollection fetchAssetCollectionsWithLocalIdentifiers:@[albumPlaceholder.localIdentifier] options:nil];
if (fetchResult.count > 0) {
saveBlock(fetchResult.firstObject);
}
} else {
NSLog(@"Error creating album: %@", error);
}
}];
}
}

我正在使用PHImageManager来获取图像。

Answer 1

要使用照片框架使用照片保存细节，您必须将图像写入临时文件，并使用CGImageDestinationAddImage将元数据添加到临时文件。

然后，您可以从临时文件中读取数据，并使用[PHAssetChangeRequest creationRequestForAssetFromImageAtFileURL]将其保存到照片库中。