使用AFNetworking的AFImageCache类强制在请求中使用缓存。以下是代码示例：

//设置图片URL请求 NSURLRequest *urlRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://example.com/image.jpg"]];

UIImage *cachedImage = [[AFImageCache sharedImageCache] cachedImageForRequest:urlRequest];

if (cachedImage) { //如果已经缓存该图像，则设置为缓存的图像 self.imageView.image = cachedImage; } else { //如果没有缓存图像，则使用setImageWithURLRequest方法请求图像，并强制使用缓存 [self.imageView setImageWithURLRequst:urlRequest placeholderImage:nil success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image) {

    self.imageView.image = image;

    //将下载的图像添加到缓存
    [[AFImageCache sharedImageCache] cacheImage:image forRequest:urlRequest];
    
} failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error) {
    NSLog(@"Error: %@", error);
} forceFromCache:YES];

}