如何在 Swift 3.0 中使用 SDWebImage 完成块？

Question

我正在使用SDWebImage 下载图像。如果图片下载成功，我想做进一步的操作。

cell.appIcon.sd_setImage(with: url, placeholderImage: UIImage.init(named: "App-Default"), completed: {(image: UIImage!, error: NSError!, cacheType: SDImageCacheType, imageURL: URL!) -> Void in
      // Perform operation. 
})

但我收到错误：

无法将类型 '(UIImage!, NSError!, SDImageCacheType, URL!) -> Void' 的值转换为预期的参数类型 'SDExternalCompletionBlock?'

Answer 1

终于解决了。

cell.appIcon.sd_setImage(with: url!, placeholderImage: UIImage(named: "App-Default"),options: SDWebImageOptions(rawValue: 0), completed: { (image, error, cacheType, imageURL) in
 // Perform operation.
}) 

Answer 2

SWIFT 4-5 版本

let url = URL(string: "http://some_url")
cell.appIcon.sd_setImage(with: url, placeholderImage: UIImage(named: "App-Default"),options: SDWebImageOptions(rawValue: 0), completed: { image, error, cacheType, imageURL in
     // your rest code
})

重要！ 不要忘记在必要时将 self 作为弱或无主（如 [self weak]/[self unowned]）发送到块中，以避免保留循环。

例子：

cell.appIcon.sd_setImage(
     with: url,
     placeholderImage: UIImage(named: "App-Default"),
     options: SDWebImageOptions(rawValue: 0),
     completed: { [self weak] image, error, cacheType, imageURL in
                  guard let selfNotNil = self else { return }
                  // your rest code
        }
)

Answer 3

更新：SWIFT 5 SDWebImage 5.x.x

        cell.imageView.sd_imageIndicator = SDWebImageActivityIndicator.gray
        cell.imageView.sd_setImage(with: url) { (image, error, cache, urls) in
            if (error != nil) {
                // Failed to load image
                cell.imageView.image = UIImage(named: "ico_placeholder")
            } else {
                // Successful in loading image
                cell.imageView.image = image
            }
        }

================================================ ==========================

cell.appIcon.sd_setImage(with: url, placeholderImage: UIImage(named: "App-Default"),options: SDWebImageOptions(rawValue: 0), completed: { (img, err, cacheType, imgURL) in
     // code
}) 

试试这个，希望能正常工作

Answer 4

根据您正在使用的框架中的typedef：

typedef void(^SDExternalCompletionBlock)(UIImage * _Nullable image, NSError * _Nullable error, SDImageCacheType cacheType, NSURL * _Nullable imageURL);

SDExternalCompletionBlock 由_Nullable 指示的可选参数组成。因此你的代码应该这样写：

cell.appIcon.sd_setImage(with: url, placeholderImage: UIImage.init(named: "App-Default"), completed: {(image: UIImage?, error: NSError?, cacheType: SDImageCacheType, imageURL: URL?) -> Void in
      // Perform operation. 
})

由于编译器知道完成块参数的类型（来自函数声明），您可以更简洁地编写代码并且（IMO）更易于阅读，如下所示：

cell.appIcon.sd_setImage(with: url, placeholderImage: UIImage(named: "App-Default"), completed: { (image, error, cacheType, imageURL) in
      // Perform operation. 
})

Answer 5

这也适用于 swift 3：

cell.appIcon.sd_setImage(with: url, placeholderImage: UIImage(named: "App-Default"), options: []) { (image, error, imageCacheType, imageUrl) in
            // Perform your operations here.
}