Question

更新我的xcode以运行swift 2后，它给了我这两个我很难解决的错误。

错误1 无法下标类型＆＃39; [String：AnyObject]的值？＆＃39;索引类型为＆＃39; String＆＃39;

代码

let image : UIImage = editingInfo[UIImagePickerControllerOriginalImage] as! UIImage

错误2 条件绑定的初始化程序必须具有可选类型，而不是＆＃39; UIImage＆＃39;

代码

if let constImage = image  (Error2 display here) 
        {
            let targetWidth = UIScreen.mainScreen().scale * UIScreen.mainScreen().bounds.size.width
            let resizedImage = constImage.resize(targetWidth)

            picker.dismissViewControllerAnimated(true, completion: {
                () -> Void in

                NetworkManager.sharedInstance.postImage(resizedImage, completionHandler: {
                    (error) -> () in

                    if let constError = error
                    {
                        self.showAlert(constError.localizedDescription)
                    }
                })

            })
        }

Answer 1

以下代码......

let image : UIImage = editingInfo[UIImagePickerControllerOriginalImage] as! UIImage

如果没有UIImagePickerControllerOriginalImage密钥或者它不是图像，

...会崩溃。

从哪里获得editingInfo？因为Swift中没有imagePickerController:didFinishPickingImage:editingInfo:。您应该使用optional func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : AnyObject])。

您在下一行的第二个错误......

if let constImage = image

...由let image: UIImage = ...行引起。您的image属于UIImage类型，而不是UIImage?。因此，它不是可选的，您无法在if let constImage = image中使用它。如果您想以这种方式使用它，则必须为UIImage?。顺便说一下，不需要使用let image: UIImage = ...，let image = ...就足够了，因为编译器可以从你的语句中推断变量类型。

将其重写为类似的内容。

func imagePickerController(picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : AnyObject]) {

  guard let image = info[UIImagePickerControllerOriginalImage] as? UIImage else {
    // throw an error, return from your function, whatever
    return
  }
  // from now you can use `image` safely
  // it does exist and it's not optional

  let targetWidth = UIScreen.mainScreen().scale * UIScreen.mainScreen().bounds.size.width
  let resizedImage = image.resize(targetWidth)

  picker.dismissViewControllerAnimated(true, completion: {
    () -> Void in

    NetworkManager.sharedInstance.postImage(resizedImage, completionHandler: {
      (error) -> () in

      if let constError = error
      {
        self.showAlert(constError.localizedDescription)
      }
    })

  })

}

以下部分......

  guard let image = info[UIImagePickerControllerOriginalImage] as? UIImage else {
    // throw an error, return from your function, whatever
    return
  }

......这样做......

info密钥的UIImagePickerControllerOriginalImage字典中是否有值？如果否，则执行else {}语句，
值是否存在，我可以将它投射到UIImage吗？如果否，则执行else {}语句，
现在我们已将info成功投放到UIImage并存储在image中，else {}语句未执行且我们的功能仍在继续。

当字典值类型为AnyObject时，如何从某种类型的字典中获取值的安全方法。

用于条件绑定的swift 2初始化程序必须具有可选类型，而不是＆＃39; UIImage＆＃39;

1 个答案: