ios - Swift 中的 Objective-C 协议(protocol)

Question

我正在使用 Fusuma cocoal pod 框架。然而，我发现他们有一个 Objective-C 协议(protocol)，甚至认为整个项目都是用 Swift 编写的。

@objc public protocol FusumaDelegate: class {

    func fusumaImageSelected(image: UIImage)
    optional func fusumaDismissedWithImage(image: UIImage)
    func fusumaVideoCompleted(withFileURL fileURL: NSURL)
    func fusumaCameraRollUnauthorized()

    optional func fusumaClosed()
}

我想在协议(protocol)中添加另一个功能。但是，我收到此警告

Method cannot be a member of an @objc protocol because the type of the parameter cannot be represented in objective-C

我正在考虑删除协议(protocol)前面的@objc，但它说我必须删除可选函数。我不介意将它们更改为正常功能，但是，我想了解如果删除 @objc 应该注意什么

我要添加的函数是之前 VC 的另一个委托(delegate)函数。在这种情况下，我有 3 个 VC。第二个是这个，在第三个 VC 被解雇后从它那里获取数据。然后我想添加如下委托(delegate)函数让VC1开始上传数据

extension FusumaViewController: VC3Delegate {
    func readyToUploadPost(postUpload: PostUpload) {
    delegate_?.readyToUploadPost_Fusuma(postUpload)
}

Answer 1

@HAS 是否说明了此协议(protocol)被赋予@objc 的最可能原因是因为 Swift 不允许您使用可选的协议(protocol)要求方法。这样做的快速方法是:

public protocol FusumaDelegate: class {

    func fusumaImageSelected(image: UIImage)
    func fusumaVideoCompleted(withFileURL fileURL: NSURL)
    func fusumaCameraRollUnauthorized()
}

extension FusumaDelegate {
    func fusumaDismissedWithImage(image: UIImage) {/*Default Implementation*/}
    func fusumaClosed() {/*Default Implementation*/}
}

当然，我想你会遇到默认实现的问题，但是:

You can use protocol extensions to provide a default implementation to any method or computed property requirement of that protocol. If a conforming type provides its own implementation of a required method or property, that implementation will be used instead of the one provided by the extension. The Swift Programming Language

这是在 Playground 上创建的，旨在为您提供一个想法，没有任何错误:

public protocol FusumaDelegate: class {
    func fusumaImageSelected(image: UIImage)
    func fusumaVideoCompleted(withFileURL fileURL: NSURL)
    func fusumaCameraRollUnauthorized()
}

extension FusumaDelegate {
    func fusumaDismissedWithImage(image: UIImage) {}
    func fusumaClosed() {}
}


class Test : UIViewController, FusumaDelegate {
    func fusumaImageSelected(image: UIImage) {
        //do stuff
    }

    func fusumaVideoCompleted(withFileURL fileURL: NSURL) {
        //do stuff
    }

    func fusumaCameraRollUnauthorized() {
        //do stuff
    }

    func fusumaDismissedWithImage(image: UIImage) {
        //do stuff
        self.fusumaClosed()
    }
}