ios - 对成员 'datatask(with:completionhandler:)' 的模糊引用

Question

我的代码有问题。我正在尝试通过 StringBuilder 下载图片，然后将其设置为 UIImage 我似乎遇到了问题，我希望有人能看到我做错了什么。

设置界面:

uiMovieTitle.text = self.movies![movieIndex].title

    var finalImageUrl = StringBuilder()

    let session = URLSession(configuration: .default)

    let downloadPicTask = session.dataTask(with: finalImageUrl) { (data, response, error) in
        // The download has finished.
        if let e = error {
            print("Error downloading cat picture: \(e)")
        } else {
            // No errors found.
            // It would be weird if we didn't have a response, so check for that too.
            if let res = response as? HTTPURLResponse {
                print("Downloaded cat picture with response code \(res.statusCode)")
                if let imageData = data {
                    // Finally convert that Data into an image and do what you wish with it.
                    let image = UIImage(data: imageData)
                    // Do something with your image.
                    uiMoviePoster.image = image
                } else {
                    print("Couldn't get image: Image is nil")
                }
            } else {
                print("Couldn't get response code for some reason")
            }
        }
    }

   downloadPicTask.resume()

}

字符串生成器

func StringBuilder() -> (String){
    let posterBase = "http://image.tmdb.org/t/p/w1920"
    let linkEnd = self.movies?[movieIndex].posterPath

    var finalLink = ""

    finalLink = posterBase + linkEnd!

    return finalLink

}

我还下载了另一个电影列表 (JSON)，这对 StringBuilder 至关重要。

Answer 1

编译器报错是因为函数 SwiftBuilder 返回一个 String 并且 URLSession 上有多个名为 dataTask(with: completion:)，但它们都没有将 String 作为第一个参数。

如果您需要 SwiftBuilder 继续为代码的其他部分返回字符串，那么在这里您需要将该字符串转换为 URL。

像下面这样的东西应该可以工作:

let session = URLSession(configuration: .default)

let imageUrlString = StringBuilder()
if let imageUrl = URL(string: imageUrlString) {
let downloadPicTask = session.dataTask(with: imageUrl) { (data, response, error) in
    // The download has finished.

等等...让我知道这是否有意义。