iOS 8照片框架.访问照片元数据

如果您请求内容编辑输入,则可以将完整图像作为a CIImage,并且CIImage具有标题properties为包含图像元数据的字典的属性.

示例Swift代码:

let options = PHContentEditingInputRequestOptions()
options.networkAccessAllowed = true //download asset metadata from iCloud if needed

asset.requestContentEditingInputWithOptions(options) { (contentEditingInput: PHContentEditingInput?, _) -> Void in
    let fullImage = CIImage(contentsOfURL: contentEditingInput!.fullSizeImageURL)

    print(fullImage.properties)
}

示例Objective-C代码:

PHContentEditingInputRequestOptions *options = [[PHContentEditingInputRequestOptions alloc] init];
options.networkAccessAllowed = YES; //download asset metadata from iCloud if needed

[asset requestContentEditingInputWithOptions:options completionHandler:^(PHContentEditingInput *contentEditingInput, NSDictionary *info) {
    CIImage *fullImage = [CIImage imageWithContentsOfURL:contentEditingInput.fullSizeImageURL];

    NSLog(@"%@", fullImage.properties.description);
}];

您将获得所需的{Exif},{TIFF},{GPS}等词典.

我发现并且对我有用的更好的解决方案是:

[[PHImageManager defaultManager] requestImageDataForAsset:photoAsset
                                                  options:reqOptions
                                            resultHandler:
         ^(NSData *imageData, NSString *dataUTI, UIImageOrientation orientation, NSDictionary *info) {
             CIImage* ciImage = [CIImage imageWithData:imageData];
             DLog(@"Metadata : %@", ciImage.properties);
         }];

我以为我会分享一些代码来使用ImageIO框架和Photos框架来阅读元数据.您必须使用PHCachingImageManager请求图像数据.

@property (strong) PHCachingImageManager *imageManager;

请求图像并使用它的数据来创建元数据字典

-(void)metadataReader{
    PHFetchResult *result = [PHAsset fetchAssetsInAssetCollection:self.myAssetCollection options:nil];
    [result enumerateObjectsAtIndexes:[NSIndexSet indexSetWithIndex:myIndex] options:NSEnumerationConcurrent usingBlock:^(PHAsset *asset, NSUInteger idx, BOOL *stop) {
        [self.imageManager requestImageDataForAsset:asset options:nil resultHandler:^(NSData *imageData, NSString *dataUTI, UIImageOrientation orientation, NSDictionary *info) {
            NSDictionary *metadata = [self metadataFromImageData:imageData];
                           NSLog(@"Metadata: %@", metadata.description);
            NSDictionary *gpsDictionary = metadata[(NSString*)kCGImagePropertyGPSDictionary];
            if(gpsDictionary){
                NSLog(@"GPS: %@", gpsDictionary.description);
            }
            NSDictionary *exifDictionary = metadata[(NSString*)kCGImagePropertyExifDictionary];
            if(exifDictionary){
                NSLog(@"EXIF: %@", exifDictionary.description);
            }

            UIImage *image = [UIImage imageWithData:imageData scale:[UIScreen mainScreen].scale];
            // assign image where ever you need...
        }];

    }];
}

将NSData转换为元数据

-(NSDictionary*)metadataFromImageData:(NSData*)imageData{
    CGImageSourceRef imageSource = CGImageSourceCreateWithData((__bridge CFDataRef)(imageData), NULL);
    if (imageSource) {
        NSDictionary *options = @{(NSString *)kCGImageSourceShouldCache : [NSNumber numberWithBool:NO]};
        CFDictionaryRef imageProperties = CGImageSourceCopyPropertiesAtIndex(imageSource, 0, (__bridge CFDictionaryRef)options);
        if (imageProperties) {
            NSDictionary *metadata = (__bridge NSDictionary *)imageProperties;
            CFRelease(imageProperties);
            CFRelease(imageSource);
            return metadata;
        }
        CFRelease(imageSource);
    }

    NSLog(@"Can't read metadata");
    return nil;
}

这具有抓取图像的开销,因此它不如枚举您的资产或集合那么快,但它至少是这样的.

PhotoKit将对元数据的访问限制为PHAsset的属性(location,creationDate,favorite,hidden,modificatonDate,pixelWidth,pixelHeight ......).原因(我怀疑)是由于引入了iCloud PhotoLibrary,图像可能不在设备上.因此,整个元数据不可用.只有这样,才能获得完整的EXIF/IPTC元数据将首先从iCloud中下载原始图像(如果不可用),然后使用的ImageIO以提取其元数据.