UIImagePickerController和从现有照片中提取EXIF数据

我正在使用这个来处理相机胶卷中的图片

-(CLLocation*)locationFromAsset:(ALAsset*)asset
{
    if (!asset)
        return nil;

    NSDictionary* pickedImageMetadata = [[asset defaultRepresentation] metadata];
    NSDictionary* gpsInfo = [pickedImageMetadata objectForKey:(__bridge NSString *)kCGImagePropertyGPSDictionary];
    if (gpsInfo){
        NSNumber* nLat = [gpsInfo objectForKey:(__bridge NSString *)kCGImagePropertyGPSLatitude];
        NSNumber* nLng = [gpsInfo objectForKey:(__bridge NSString *)kCGImagePropertyGPSLongitude];
        if (nLat && nLng)
            return [[CLLocation alloc]initWithLatitude:[nLat doubleValue] longitude:[nLng doubleValue]];
    }

    return nil;
}


-(void) imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    //UIImage *image =  [info objectForKey:UIImagePickerControllerOriginalImage];
    NSURL *assetURL = [info objectForKey:UIImagePickerControllerReferenceURL];

    // create the asset library in the init method of your custom object or view controller
    //self.library = [[ALAssetsLibrary alloc] init];
    //

    [self.library assetForURL:assetURL resultBlock:^(ALAsset *asset) {

        // try to retrieve gps metadata coordinates
        CLLocation* myLocation = [self locationFromAsset:asset];

        // Do your stuff....

    } failureBlock:^(NSError *error) {
        NSLog(@"Failed to get asset from library");
    }];
}

如果图像包含GPS元数据，则显然可以正常工作

希望这能有所帮助

仅仅是一个想法，不过你有没有尝试在GitHub上的Three20项目中使用TTPhotoViewController呢？

它提供了一个可以从多个来源读取的图片选择器。你也许可以将其用作UIImagePickerController的替代方案，或者该源代码可能会给你一些提示，如何获取所需的信息。

你想从图像中提取位置数据的具体原因是什么？另一种选择是使用CoreLocation框架单独获取位置。如果你只需要地理数据，这可能会为你节省一些麻烦。

看起来由UIImagePickerControllerMediaURL获取的照片根本没有exif标签

您可以尝试对UIImagePickerController返回的图像数据和目录中的每个图像进行哈希处理，然后进行比较。

iOS 10 - Swift 3

选择器的回调函数有一个 info 字典，其中包含一个关键字 metadata：UIImagePickerControllerMediaMetadata

如果您仍需要支持iOS 8，则此代码是使用Swift 3编写的：

import AssetsLibrary

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {

    if picker.sourceType == UIImagePickerControllerSourceType.photoLibrary,
        let url = info[UIImagePickerControllerReferenceURL] as? URL {

        let assetLibrary = ALAssetsLibrary()
        assetLibrary.asset(for: url, resultBlock: { (asset) in
            if let asset = asset {
                let assetRep: ALAssetRepresentation = asset.defaultRepresentation()
                let metaData: NSDictionary = assetRep.metadata() as NSDictionary
                print(metaData)
            }
        }, failureBlock: { (error) in
            print(error!)
        })
    }

}

做这件事的捷径是遍历UIImagePickerViewController的视图，并在委托回调中选择选定的图像。

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {

  id thumbnailView = [[[[[[[[[[picker.view subviews] 
                  objectAtIndex:0] subviews]
                  objectAtIndex:0] subviews]
                objectAtIndex:0] subviews]
                objectAtIndex:0] subviews]
              objectAtIndex:0];

  NSString *fullSizePath = [[[thumbnailView selectedPhoto] fileGroup] pathForFullSizeImage];
  NSString *thumbnailPath = [[[thumbnailView selectedPhoto] fileGroup] pathForThumbnailFile];

  NSLog(@"%@ and %@", fullSizePath, thumbnailPath);

}