相关疑难解决方法(0)

我有一个带自定义单元格的UITableView.我使用Grand Central Dispatch异步加载图像.一切正常,但是当我向下滚动时,会显示先前加载的图像,直到下载新图像.这是我的代码:

if (![[NSFileManager defaultManager] fileExistsAtPath:[path stringByAppendingPathComponent:@"image.png"]])
{
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH,  0ul);
    dispatch_async(queue, ^{
        NSString *url=[pat stringByAppendingPathComponent:@"comments.txt"];
        NSString *u=[NSString stringWithContentsOfFile:url encoding:NSUTF8StringEncoding error:nil];
        NSURL *imageURL=[NSURL URLWithString:u];
        NSData *image=[NSData dataWithContentsOfURL:imageURL];
        [image writeToFile:[pat stringByAppendingPathComponent:@"image.png"] atomically:YES];
        dispatch_sync(dispatch_get_main_queue(), ^{
            cell.imageView.image=[UIImage imageWithContentsOfFile:[pat stringByAppendingPathComponent:@"image.png"]];
            [cell setNeedsLayout];
            NSLog(@"Download");
        });
    });
}
else
{
    NSLog(@"cache");
    cell.imageView.image=[UIImage imageWithContentsOfFile:[pat stringByAppendingPathComponent:@"image.png"]];
}

任何建议赞赏.PS我重用了细胞

我从github 使用这个项目,它是一个图像选择器.我不得不做一个非常小的改动,因为ios7使你的专辑中的预览图像再次显示但是现在当你离开选择器然后回到它时所选择的照片(2/5)重置为0/5甚至虽然我选择了照片.我怎样才能解决这个问题？

在dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0)似乎一直无法进行更新UI即使dispatch_async(dispatch_get_main_queue()重新加载它里面的UI.当我注释掉dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0)这些图片时会立即加载,但其他东西会因为队列而被破坏.

这里是代码片段,dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0) 我改变了代码我改变了注释掉了

AGIPCAssetsController.m:

- (void)loadAssets
{
    [self.assets removeAllObjects];

    __ag_weak AGIPCAssetsController *weakSelf = self;

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0), ^{

        __strong AGIPCAssetsController *strongSelf = weakSelf;

        @autoreleasepool {
            [strongSelf.assetsGroup enumerateAssetsUsingBlock:^(ALAsset *result, NSUInteger index, BOOL *stop) {

                if (result == nil) 
                {
                    return;
                }

                AGIPCGridItem *gridItem = [[AGIPCGridItem alloc] initWithImagePickerController:strongSelf.imagePickerController asset:result andDelegate:strongSelf];
                if ( strongSelf.imagePickerController.selection != nil && 
                    [strongSelf.imagePickerController.selection containsObject:result])
                {
                    gridItem.selected = YES;
                }
                [strongSelf.assets addObject:gridItem];
            }];
        }

        dispatch_async(dispatch_get_main_queue(), …