SDWebImage文档表示它会自动缓存.至于缩放，有很多的净代码像这样大约.诀窍是将其与SDWebImage集成.幸运的是，它提供了一个完成块:

SDWebImage docs says it caches automatically. As for scaling, there's plenty of net code like this around. The trick is integrating it with SDWebImage. Fortunately, it provides a completion block:

NSURL *url = /* prepare a url... see note below */
[myCell.homeImage setImageWithURL:url
               placeholderImage:[UIImage imageNamed:@"menuButton.png"]
                      completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType) {
    // inspect cacheType here to make sure it's cached as you want it
    myCell.homeImage.image = [self scaleImage:image toSize:CGSizeMake(75,75)];
}];

一个简单的标尺看起来像这样(未经测试):

A simple scale would look something like this (not tested):

- (UIImage *)scale:(UIImage *)image toSize:(CGSize)size {
    UIGraphicsBeginImageContextWithOptions(size, NO, 0.0);
    [image drawInRect:CGRectMake(0, 0, size.width, size.height)];
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();    
    UIGraphicsEndImageContext();
    return newImage;
}

偶然地，我注意到您使用通用字符串操作来构建URL.您***对字符串使用专门的方法，如下所示:

Incidentally, I notice that you use generic string manipulation to build the URL. You'd be better off using the specialized methods on string as follows:

// this can be defined outside cellForRowAtIndexPath
NSURL *baseUrl = [NSURL urlWithString:@"http://example.com/"];

NSString *imageItemName = [homeImages objectAtIndex:row];
NSURL *url = [NSURL URLWithString:imageItemName relativeToURL:baseURL];