IOS Swift assetForURL 错误

Question

我只想使用 Swift 从 ios 8 中的 ALAsset 获取图像资源。

我使用 SNImagePicker 进行多张图片选取。

对于 objective-c，我使用这个:

    for (int i = 0; i < info.count; i++) {
    ALAssetsLibrary *assetLibrary=[[ALAssetsLibrary alloc] init];
    [assetLibrary assetForURL:info[i] resultBlock:^(ALAsset *asset) {
        UIImage *image = [UIImage imageWithCGImage:[asset aspectRatioThumbnail]];
    } failureBlock:^(NSError *error) {     }];

使用 swift，我尝试这样做:

func imagePicker(imagePicker: SNImagePickerNC!, didFinishPickingWithMediaInfo info: NSMutableArray!){
    var i: Int = Int(0);
    for (i; i < info.count as Int; i++){
        var url: NSURL = info[i] as NSURL
        var assetLibrary: ALAssetsLibrary = ALAssetsLibrary()

        //
        //assetLibrary.assetForURL(NSURL?(), resultBlock: ALAssetsLibraryAssetForURLResultBlock?(), failureBlock: ALAssetsLibraryAccessFailureBlock?())            
        //

        assetLibrary.assetForURL(url, resultBlock: {
            (asset: ALAsset!) in
            if asset != nil {
                var assetRep: ALAssetRepresentation = asset.defaultRepresentation()
                var iref = assetRep.fullResolutionImage().takeUnretainedValue()
                var image =  UIImage(CGImage: iref)

                self.imageViewPreview.contentMode = UIViewContentMode.ScaleAspectFill
                self.imageViewPreview.image = image

            }
            }, failureBlock: {
                (error: NSError!) in

                NSLog("Error!", nil)
            }
        )
    }
}

通过这段代码，我得到了一个错误:

Type 'CVarArg' does not conform to protocol 'NilLiteralConvertible'

Answer 1

尝试用 NSLog("Error!") 替换 NSLog("Error!", nil)。此语句导致 Swift 抛出意外错误消息。