Question

我使用ELCImagePickerController获取图片的网址。我存储了该URL以供将来参考。

我使用以下网址获取该网址：

[dict valueForKey:UIImagePickerControllerReferenceURL];

现在问题出现在一段时间后用户从照片库中删除了该特定图像我将使用URL访问该图像。我的应用程序没有崩溃。

我尝试过使用NSUrl方法

[imagePath checkResourceIsReachableAndReturnError:&err]

我尝试了类似的事情：

-(BOOL)findImage:(NSURL*)path
{
    dispatch_group_t group = dispatch_group_create();
    dispatch_group_enter(group);
    __block BOOL flag=YES;
    ALAssetsLibraryAssetForURLResultBlock resultblock = ^(ALAsset *myasset)
    {
        ALAssetRepresentation *rep = [myasset defaultRepresentation];
        CGImageRef iref = [rep fullScreenImage];
        if (iref) {
            flag=YES;
            dispatch_group_leave(group);
        }
    };
    ALAssetsLibraryAccessFailureBlock failureblock  = ^(NSError *myerror)
    {
        NSLog(@"cant get image - %@",[myerror localizedDescription]);
        flag=NO;
    };
    ALAssetsLibrary* assetslibrary = [[ALAssetsLibrary alloc] init];
    [assetslibrary assetForURL:path resultBlock:resultblock failureBlock:failureblock];

    dispatch_group_wait(group, DISPATCH_TIME_FOREVER);
    dispatch_release(group);
    [assetslibrary release];

    return flag;
}

示例网址：

assets-library://asset/asset.JPG?id=E862927E-E646-448A-9EB6-A7D48668B3DC&ext=JPG

但没有成功。

如何知道特定网址上的图片。

如果任何人可以帮助我，这将是值得注意的。

提前致谢。

Answer 1

对于这种情况，您需要检查ALAssetRepresentation * rep = [myasset defaultRepresentation]为nil。

if(rep != nil){ //write your code.. }

Answer 2

解决了 findImage 方法

中的更改问题

-(BOOL)findImage:(NSURL*)path
{
    dispatch_group_t group = dispatch_group_create();
    dispatch_group_enter(group);
    __block BOOL flag=YES;
    ALAssetsLibrary* assetslibrary = [[ALAssetsLibrary alloc] init];
    [assetslibrary assetForURL:path resultBlock:^(ALAsset *asset) {
        if (asset==nil)
        {
            flag=NO;
        }
        else
        {
            flag=YES;
        }
            dispatch_group_leave(group);
        } failureBlock:^(NSError *error){
                NSLog(@"operation was not successfull!");
                dispatch_group_leave(group);
    }];
    dispatch_group_wait(group, DISPATCH_TIME_FOREVER);
    dispatch_release(group);
    [assetslibrary release];
    return flag;
}

如何知道网址上的图像

2 个答案: