UITableView中的图像会在滚动时不断重新加载和错误的图像闪烁 [英] Images in UITableView keep re-loading and wrong images flash while scrolling

问题描述

我创建了一个UITableView，它从URL请求中填充每个单元格。我使用'dispatch_queue'来阻止UItableView冻结。出于某种原因，当我滚动浏览UITableView时，图像会闪烁并消失并填充错误的单元格一秒钟，然后自行修复。这是我的代码。我使用restkit提取订阅源

i have created a UITableView which populates each cell from URL requests. I have used 'dispatch_queue' to prevent the UItableView from freezing. For some reason when i scroll through the UITableView the images flash and disappear and fill the wrong cell for a second until fixing themselves. Here is my code. I am pulling the feed using restkit

customCell.customCellTextLabel.text = [NSString stringWithFormat:@"%@",feedO.title];

    NSString *string = [NSString stringWithFormat:@"%@",feedO.body];

    NSURL *urlString;

        NSDataDetector *linkDetector = [NSDataDetector dataDetectorWithTypes:NSTextCheckingTypeLink error:nil];
        NSArray *matches = [linkDetector matchesInString:string options:0 range:NSMakeRange(0, [string length])];
        for (NSTextCheckingResult *match in matches) {
            if ([match resultType] == NSTextCheckingTypeLink) {
                urlString = [match URL];
                NSLog(@"found Body URL: %@ and title %@", urlString,feedO.title);
            }
        }

        dispatch_queue_t imageQueue = dispatch_queue_create("imageDownloader",nil);
        dispatch_async(imageQueue, ^{

            NSData *data = [[NSData alloc] initWithContentsOfURL:urlString];

            dispatch_async(dispatch_get_main_queue(), ^{

                customCell.customCellImageView.image = [UIImage imageWithData: data];
            });
        });


    return customCell;

推荐答案

你应该考虑使用这个库SDWebImage，可以在这里找到<针对这类问题，请使用href =https://github.com/rs/SDWebImage =nofollow> https://github.com/rs/SDWebImage 。它非常容易处理远程图像的异步下载和缓存。

You should consider using this library SDWebImage, available here https://github.com/rs/SDWebImage for that kind of problems. It handles asynchronous download and cache for remote images very easily.

最简单的安装是通过使用CocoaPods完成的

The simpliest installation is done by using CocoaPods

CocoaPods（ http://cocoapods.org ）是Objective-C的依赖管理器，它自动化并简化了使用过程项目中的第三方库。
有关详细信息，请参阅使用入门部分。

CocoaPods (http://cocoapods.org) is a dependency manager for Objective-C, which automates and simplifies the process of using 3rd-party libraries in your projects. See the Get Started section for more details.

在您的Podfile中使用

Use in your Podfile

platform :ios, '6.1'
pod 'SDWebImage', '~>3.6'

在安装SDWebImage的依赖项之后，只需在视图控制器中使用以下行：

After installing the dependency for SDWebImage, just simply use the following lines in your view controller :

#import <SDWebImage/UIImageView+WebCache.h>

...

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *MyIdentifier = @"MyIdentifier";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:MyIdentifier];

    if (cell == nil)
    {
        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault
                                       reuseIdentifier:MyIdentifier] autorelease];
    }

    // Here we use the new provided setImageWithURL: method to load the web image
    [cell.imageView setImageWithURL:[NSURL URLWithString:@"http://www.domain.com/path/to/image.jpg"]
                   placeholderImage:[UIImage imageNamed:@"placeholder.png"]];

    cell.textLabel.text = @"My Text";
    return cell;
}

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