ios - 如何将iOS图片库(ALAssetsLibrary)中的图片文件复制到App本地目录？

Question

我可以通过 ALAssetsLibrary 从照片库中获取图像:

void (^assetEnumerator)(ALAsset *, NSUInteger, BOOL *) = ^(ALAsset *result, NSUInteger index, BOOL *stop){
        if([[result valueForProperty:ALAssetPropertyType] isEqualToString:ALAssetTypePhoto]) {
            // Copy the photo image to the `/Documents` directory of this App here

        }
    };

    void (^assetGroupEnumerator )(ALAssetsGroup*, BOOL*) = ^(ALAssetsGroup *group, BOOL *stop){
        if (group != nil) {
            [group enumerateAssetsUsingBlock:assetEnumerator];
        }
    };
    // fetch
    ALAssetsLibrary *library = [ALAssetsLibrary new];
    [library enumerateGroupsWithTypes:ALAssetsGroupAll usingBlock:assetGroupEnumerator failureBlock:^(NSError *error) {
        NSLog(@"failed");
    }];

我想将特定图像复制到本地目录 (App_home/Documents)，但我不知道如何通过处理 ALAsset 对象来完成这项工作。

Answer 1

试试下面的代码

ALAssetsLibrary *assetLibrary=[[ALAssetsLibrary alloc] init];
[assetLibrary assetForURL:YourURL resultBlock:^(ALAsset *asset) 
    {
       ALAssetRepresentation *rep = [asset defaultRepresentation];
       Byte *buffer = (Byte*)malloc(rep.size);
       NSUInteger buffered = [rep getBytes:buffer fromOffset: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]);

    }
];

获取文档目录下的图片

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *newPath = [documentsDirectory stringByAppendingPathComponent:@"Your_Image_Name"];
UIImage *myImg = [UIImage imageWithContentsOfFile:newPath]