仅当图像无法加载SDWebImage时才设置占位符图像

Question

我想显示imageview的背景颜色,直到下载正在进行,如果下载失败或图像不可用,那么我想显示占位符图像.我怎样才能实现这一目标？

主要目的是稍后在加载期间不设置图像.

谢谢

Answer 1

来自SDWebImage 文档:

使用块

使用块,您可以收到有关图像下载进度以及图像检索成功与否的通知:

// Here we use the new provided sd_setImageWithURL: method to load the web image

对于Swift:

cell.imageView.sd_setImageWithURL(url, placeholderImage:nil, completed: { (image, error, cacheType, url) -> Void in
            if (error) {
                // set the placeholder image here

            } else {
                // success ... use the image
            }
        })

对于Objective-C

    [cell.imageView sd_setImageWithURL:[NSURL URLWithString:@"http://www.domain.com/path/to/image.jpg"]
                      placeholderImage:nil
                             completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, NSURL *imageURL) {
                                    if (error) {
                                      self.imageView.image = [UIImage imageNamed:@"placeHolderImage"];
                                    }
                                 }];

Answer 2

Swift 3解决方案：

cell.imageView?.sd_setImage(with: url) { (image, error, cache, urls) in
            if (error != nil) {
                cell.imageView.image = UIImage(named: "ico_placeholder")
            } else {
                cell.imageView.image = image
            }
}

目标C的解决方案：

[cell.imageView sd_setImageWithURL:url
                  placeholderImage:nil
                         completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, NSURL *imageURL) {
                                if (error) {
                                  self.imageView.image = [UIImage imageNamed:@"ico_placeholder"];
                                } else {
                                  self.imageView.image = image;
                                }
}];

希望你们觉得这有用。