如何在协议扩展中正确使用 'self' 以避免必须使用协议存根？

Question

目前我们有一个协议和一个协议扩展：

protocol Camera: UIImagePickerControllerDelegate, UINavigationControllerDelegate {

  func openTheCamera()
}

extension Camera where Self: UIImagePickerController {
    func openTheCamera() {
        if UIImagePickerController.isSourceTypeAvailable(.camera) {
            let imagePicker = UIImagePickerController()
            imagePicker.delegate = self
            imagePicker.sourceType = .camera
            imagePicker.allowsEditing = false
            self.present(imagePicker, animated: true, completion: nil)
        }
    }
}

由于该函数已经在协议扩展中定义，我尝试在符合 class:

的情况下直接调用它

class SomeClass: Camera {

 override func viewDidLoad() {
        super.viewDidLoad()
        openTheCamera()
    }
}

问题是当我尝试符合 class 时出现错误：

Typ UIViewController does not conform to protocol 'Camera' Do you want to add protocol stubs?

问题是 func 已经在扩展中定义了，我不想再将它添加到控制器中。如果我添加协议存根 (openTheCamera(){ }) 并在控制器中留空，那么我在协议扩展中定义的函数不会被执行。

Answer 1

协议条件错误。你应该使用：

extension Camera where Self: UIViewController {

如何在协议扩展中正确使用 'self' 以避免必须使用协议存根？

How to properly use 'self' in a protocol extension to avoid having to use protocol stubs?

protocols

ios

swift

swift-protocols