iphone - 如何使用 ALAssetsLibrary 将图像路径转换为 ​​uiimage

Question

我的 iphone 应用程序有一个数组用于存储用户表单库选择的图像路径。我想使用 ALAssetsLibrary 将数组中的所有图像路径转换为 ​​uiimage。我该怎么做这个动作？我尝试使用循环，但不能。感谢您的帮助。

ALAssetsLibrary *library = [[[ALAssetsLibrary alloc] init] autorelease];
[library assetForURL:[filePath objectAtIndex:0] resultBlock:^(ALAsset *asset) {
    UIImage *image = [UIImage imageWithCGImage:[[asset defaultRepresentation] fullResolutionImage]];
    [fileImage addObject:image];
} failureBlock:^(NSError *error) {

}];

Answer 1

请使用以下代码

typedef void (^ALAssetsLibraryAssetForURLResultBlock)(ALAsset *asset);
typedef void (^ALAssetsLibraryAccessFailureBlock)(NSError *error);    
                       
ALAssetsLibraryAssetForURLResultBlock resultblock = ^(ALAsset *myasset){
                       
 ALAssetRepresentation *rep = [myasset defaultRepresentation];
 CGImageRef iref = [rep fullResolutionImage];
            
 if (iref){

         dispatch_async(dispatch_get_main_queue(), ^{
             UIImage *myImage = [UIImage imageWithCGImage:iref scale:[rep scale] orientation:(UIImageOrientation)[rep orientation]];
             [fileImage addObject:myImage];
             //binding ur UI elements in main queue for fast execution
             //self.imageView.image = myImage;
         });

                                
         }      
};      
                       
ALAssetsLibraryAccessFailureBlock failureblock  = ^(NSError *myerror){
                       
     //failed to get image.
};                          
                       
ALAssetsLibrary* assetslibrary = [[[ALAssetsLibrary alloc] init] autorelease];
[assetslibrary assetForURL:[filePath objectAtIndex:0] resultBlock:resultblock failureBlock:failureblock];

注意：确保您的[filePath objectAtIndex:0]将是一个NSUrl对象。如果不是，请将其转换为NSUrl。

例子：

ALAssetsLibrary* assetslibrary = [[[ALAssetsLibrary alloc] init] autorelease];

NSURL myAssetUrl = [NSURL URLWithString:[filePath objectAtIndex:0]];

assetslibrary assetForURL:myAssetUrl resultBlock:resultblock failureBlock:failureblock];