UIImagePickerControllerでイメージピッカーからExif情報を抜き出す

didFinishPickingImage.m

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingImage:(UIImage *)image editingInfo:(NSDictionary *)editingInfo {
    NSLog(@"imagePickerController - %@", image.description);

    UIImage *editedImage = [editingInfo objectForKey:UIImagePickerControllerEditedImage];
    UIImage *originalImage = [editingInfo objectForKey:UIImagePickerControllerOriginalImage];

    __weak CameraViewController *__self = self;
    NSURL *assetURL = [editingInfo objectForKey:UIImagePickerControllerReferenceURL];
    ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
    [library assetForURL:assetURL
             resultBlock:^(ALAsset *asset) {
                 ALAssetRepresentation *representation = [asset defaultRepresentation];
                 NSDictionary *metadataDict = [representation metadata]; // ←ここにExifとかGPSの情報が入ってる
                 __self.exif = [metadataDict objectForKey:@"{Exif}"];

                 // イメージピッカーを隠す
                 [__self dismissModalViewControllerAnimated:NO];

                 // ここでプレビュー画面を開く
                 [__self showCameraConfirmView:image isAlbum:YES exif:__self.exif];

                 NSLog(@"[metadataDict objectForKey:@\"Exif\"] - %@", [metadataDict objectForKey:@"{Exif}"]);
             } failureBlock:^(NSError *error) {
        NSLog(@"ALAssetsLibrary error - %@", error);
        // エラーの場合はExifは無視する
        __self.exif = nil;

        // イメージピッカーを隠す
        [__self dismissModalViewControllerAnimated:NO];

        // ここでプレビュー画面を開く
        [__self showCameraConfirmView:originalImage isAlbum:YES exif:__self.exif];
    }];
}