如何从 UIImagePickerControllerReferenceURL 获取数据？

Question

我在我的应用程序中使用ELCImagePickerController，我不想将选定的 fullScreenImage 保存到我的数组中，因为如果我选择了 40 张 iPad 图像，那就不好了。

我想从方法- (void)elcImagePickerController:(ELCImagePickerController *)picker didFinishPickingMediaWithInfo:(NSArray *)info 的字典中从UIImagePickerControllerReferenceURL 而不是UIImagePickerControllerOriginalImage 获取数据。

我试过了：

NSDictionary *dict = [info objectAtIndex:count];            

NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:[NSString stringWithFormat:@"%@",[dict objectForKey:@"UIImagePickerControllerReferenceURL"]]]];//UIImagePNGRepresentation([UIImage imageWithContentsOfFile:[NSString stringWithFormat:@"%@",[dict objectForKey:@"UIImagePickerControllerReferenceURL"]]] );
        NSLog(@"length %d",[data length]);
        imageview.image = [UIImage imageWithData:data];

但是，每次我得到 0 个字节。我已经尝试了论坛中所有可用的答案，但没有用。

谁能回答这个问题？

Answer 1

UIImagePickerControllerReferenceURL 返回NSURL 对象而不是字符串对象。请将您的代码更改为 -

NSData *data = [NSData dataWithContentsOfURL:[dict objectForKey:@"UIImagePickerControllerReferenceURL"]];
NSLog(@"length %d",[data length]);
imageview.image = [UIImage imageWithData:data];

UIImagePickerControllerReferenceURL为Assets Library返回NSURL对象，所以你可以得到图像-

ALAssetsLibrary *assetLibrary=[[ALAssetsLibrary alloc] init];
[assetLibrary assetForURL:[[self.imagedata objectAtIndex:i] valueForKey:UIImagePickerControllerReferenceURL] resultBlock:^(ALAsset *asset) {
    ALAssetRepresentation *rep = [asset defaultRepresentation];
    Byte *buffer = (Byte*)malloc(rep.size);
    NSUInteger buffered = [rep getBytes:buffer fromOffset:0.0 length:rep.size error:nil];
    NSData *data = [NSData dataWithBytesNoCopy:buffer length:buffered freeWhenDone:YES];//this is NSData may be what you want
    [data writeToFile:photoFile atomically:YES];//you can save image later
} failureBlock:^(NSError *err) {
    NSLog(@"Error: %@",[err localizedDescription]);
}];

注意：ALAssetsLibrary 在 iOS 9 中已弃用。

Answer 2

这个问题在 Google 上的 UIImagePickerControllerReferenceURL 排名很高，所以我想我会在 iOS9 及更高版本中添加正确的使用 UIImagePickerControllerReferenceURL 的方法，因为 ALAssetLibrary 已被弃用，以支持照片框架。

使用来自imagePickerController(_:didFinishPickingMediaWithInfo:) 的信息字典中提供的UIImagePickerControllerReferenceURL 访问照片的正确方法是通过照片工具包PHAsset。

UIImagePickerControllerDelegate 利用 Photos Framework 获取 UIImage 的基本实现如下所示：

class YourViewController: UIViewController, UIImagePickerControllerDelegate
{
    public func imagePickerController(picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : AnyObject]?) {
        guard let info = info, let url = info[UIImagePickerControllerReferenceURL] as? NSURL else {
            // Using sourceType .Camea will end up in here as there is no UIImagePickerControllerReferenceURL
            picker.dismissViewControllerAnimated(true) {}
            return
        }

        let fetchResult = PHAsset.fetchAssetsWithALAssetURLs([url], options: nil)
        if let photo = fetchResult.firstObject as? PHAsset {
            PHImageManager.defaultManager().requestImageForAsset(photo, targetSize: PHImageManagerMaximumSize, contentMode: .AspectFill, options: nil) {
                image, info in
                // At this point you have a UIImage instance as image
            }
        }
    }
}

当 sourceType 为 .Camera 时，上面的代码不会处理回调，因为信息字典不包含 UIImagePickerControllerReferenceURL。

Answer 3

在 ELCImagePickers "Selected assets" 中你可以做

-(void)selectedAssets:(NSArray*)_assets {

"... your code .?.?."

    NSMutableArray *returnArray = [[NSMutableArray alloc] init];

    for(ALAsset *asset in _assets) {

        NSMutableDictionary *workingDictionary = [[NSMutableDictionary alloc] init];
        [workingDictionary setObject:[[asset valueForProperty:ALAssetPropertyURLs] valueForKey:[[[asset valueForProperty:ALAssetPropertyURLs] allKeys] objectAtIndex:0]] forKey:@"UIImagePickerControllerReferenceURL"];

".. any other properties you need ?"

        [returnArray addObject:workingDictionary];

    }
}

然后在你的其他类中从数组中保存

- (void) importImagesFromArray:(NSArray *)_images toFolder:(NSString *)folderPath
{
   if ([_images count] > 0) {

    //... YOUR CODE HERE FOR CHECKING YOUR ARRAY...Maybe a loop or something//
    //
    //
    //

    //ex:

ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
    for (NSDictionary *dict in _images) {



        [library assetForURL:[dict objectForKey:@"UIImagePickerControllerReferenceURL"]
                 resultBlock:^(ALAsset *asset){

                     //You Can Use This

                     UIImage *theImage = [UIImage imageWithCGImage:[[asset defaultRepresentation] fullResolutionImage]
                                                             scale:1.0
                                                       orientation:[[asset valueForProperty:@"ALAssetPropertyOrientation"] intValue]];

                     //[....save image blah blah blah...];

                     ///////////////////////////////////////////////////
                     ///////////////////////////////////////////////////

                     ////// OR YOU CAN USE THIS////////////////////

                     ALAssetRepresentation *rep = [asset defaultRepresentation];
                     Byte *buffer = (Byte*)malloc(rep.size);
                     NSUInteger buffered = [rep getBytes:buffer fromOffset:0.0 length:rep.size error:nil];
                     NSData *data = [NSData dataWithBytesNoCopy:buffer length:buffered freeWhenDone:YES];//this is NSData may be what you want
                     [data writeToFile:[folderPath stringByAppendingPathComponent:@"Some Filename You Need To Assign"] atomically:YES];


                 }

                failureBlock:^(NSError *error){
                    NSLog(@"Error saving image");

                }];

        // Dont forget to release library

    }
}
}