Question

我正在学习斯坦福大学的iOS开发课程，并将我在课程中完美运行的示例代码复制到我的Xcode中。该视图不显示网址图片，我已将“允许任意负载信息”设置为＆＃34;是＆＃34;。屏幕上没有显示错误，但视图没有显示任何内容。

  class ImageViewController: UIViewController

    {

    var imageURL: URL? {
       didSet {
         image = nil
            if view.window != nil {
             fetchImage()
            }
        }
    }

    private func fetchImage() {
         if let url = imageURL {
         let urlContents = try? Data(contentsOf: url)
           if let imageData = urlContents {
              image = UIImage(data: imageData)
           }
        }
    }

override func viewDidLoad() {
    super.viewDidLoad()
    imageURL = DemoURL.stanford // for demo/testing purposes only 


 //This is the url image. It is in another swift file，the address is ( static let stanford = URL(string: "http://stanford.edu/about/images/intro_about.jpg"，) I can open it in safari.

}

override func viewWillAppear(_ animated: Bool) {
   super.viewWillAppear(animated)
    if image == nil { // we're about to appear on screen so, if needed,
      fetchImage() // fetch image
    }
}


fileprivate var imageView = UIImageView()
private var image: UIImage? {
       get {
          return imageView.image
         }
       set {
      imageView.image = newValue
      imageView.sizeToFit()
    // careful here because scrollView might be nil
    // (for example, if we're setting our image as part of a prepare)
    // so use optional chaining to do nothing
      // if our scrollView outlet has not yet been set

     }
   }
}

提前致谢。

Answer 1

来自DemoURL.swift的网址不存在......例如，你可以在DemoURL.swift中写一下：

static let stanford = URL(string:"http://upload.wikimedia.org/wikipedia/commons/thumb/c/cd/Stanford_Oval_May_2011_panorama.jpg/800px-Stanford_Oval_May_2011_panorama.jpg")

Answer 2

1）不要使用同步通话：

见： https://developer.apple.com/documentation/foundation/nsdata/1407864-init

2）以这种方式使用NSURL会话：

let myURL = URL(string: "https: ......")        
let session = URLSession.shared
let task = session.dataTask(with: myURL!) { (data, resp, err) in

        var statusCode: NSInteger = 0
        if let httpResponse : HTTPURLResponse = resp as? HTTPURLResponse{
            statusCode = httpResponse.statusCode
        }

        if let data = data, statusCode == 200{
            if let img = UIImage(data: data){
            // use your image...

           }
        }
    }

3）不要使用http，Apple要求https，因为ios9。

xcode视图不显示网址图片

2 个答案: