初始化器在继承 NSURLSession Swift 时不会覆盖指定的初始化器 [英] Initializer does not override a designated initializer while subclassing NSURLSession Swift

问题描述

我想继承 NSURLSession 类，但我在初始化时遇到问题.基本上我覆盖构造函数并在那里初始化常量 authUrl 然后调用父 init 方法.

I want to subclass NSURLSession class, but I have problem with initialisation. Basically I override the constructor and initialising the constant authUrl there then calling the parent init method.

class NSURLAuthSession: NSURLSession {
    let authUrl:NSURL;

    //Error: Initializer does not override a designated initializer from its superclass
    override init(configuration: NSURLSessionConfiguration, delegate: NSURLSessionDelegate?, delegateQueue queue: NSOperationQueue?){
        self.authUrl = NSURL.URLWithBaseURLString("http://192.168.10.105:8888/api/v1", pathSegments: ["users", "login"])!
        super.init(configuration: configuration, delegate: delegate, delegateQueue: queue)
    }
}

从 NSURLSession 的源代码中我发现它有两个初始化器:

From the source code of NSURLSession I found out that it has two initializers:

public /*not inherited*/ init(configuration: NSURLSessionConfiguration)
public /*not inherited*/ init(configuration: NSURLSessionConfiguration, delegate: NSURLSessionDelegate?, delegateQueue queue: NSOperationQueue?)

我希望最长的"init 是指定的初始化程序，但事实并非如此.我怀疑指定的初始化程序是在源代码中甚至没有指定的 init() .如何覆盖初始化程序并设置配置 NSURLSessionConfiguration?

I expected the "longest" init to be the designated initializer but it's not. I suspect that that designated initializer is the init() that is not even specified in the source code. How can I override the initializer and set up the configuration NSURLSessionConfiguration?

推荐答案

你不能.

唯一指定的初始值设定项是 NSURLSession.init() 并且您必须从您的子类初始值设定项中调用它.NSURLSession configuration、delegate 和 delegateQueue 属性是只读的，所以你不能手动设置它们.

The only designated initializer is NSURLSession.init() and you must call it from your subclass initializer. NSURLSession configuration, delegate and delegateQueue properties are read-only so you can not manually set them.

更好的方法是用自定义类包装 NSURLSession:

The better way is to wrap NSURLSession with custom class:

class NSURLAuthSession {
    private let urlSession: NSURLSession

    init(urlSession: NSURLSession) {
        self.urlSession = urlSession
    }
}

因此您将拥有更多控制和自定义选项.

thus you will have more control and customization options.

这篇关于初始化器在继承 NSURLSession Swift 时不会覆盖指定的初始化器的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！