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swift - 结构内部的变异函数

问题描述

我正在使用 Swift 4，我有一个使用默认值初始化的结构。我在里面创建了一个函数，它应该读取 JSON 并用它得到的内容更改这些默认值，但它似乎不起作用。

错误：闭包不能隐式捕获变异的自我参数

代码：

struct Workspace: Decodable {
    var guid: String
    var name: String

private enum CodingKeys : String, CodingKey {
    case guid = "guid"
    case name = "name"
}

init(){
    self.guid = "blbl"
    self.name = "oops"
}

mutating func getUserWorkspace(base: String, completed: @escaping () -> ()){
    let url = URL(string: "some url")!
    var request = URLRequest(url: url)

    request.addValue("Basic \(base)", forHTTPHeaderField: "Authorization")
    request.addValue("application/json", forHTTPHeaderField: "Accept")

    URLSession.shared.dataTask(with: request){ (data, response, error) in
        if error == nil {
            do {
                let res: Workspace = try JSONDecoder().decode(Workspace.self, from: data!)
                self.guid = res.guid  //Error here
                self.name = res.name  //Error here
                DispatchQueue.main.async {
                    completed()
                }
            }catch {
                print ("JSON error")
            }
        }
    }.resume()
}

我将 let 更改为 var，但我想还有一些我不明白的地方..

标签： swiftstructuremutating-function

解决方案

//Try this one and let me know
struct Workspace: Decodable {
    static var shared = Workspace()
    var guid: String
    var name: String

    private enum CodingKeys : String, CodingKey {
        case guid = "guid"
        case name = "name"
    }

    init(){
        self.guid = "blbl"
        self.name = "oops"
    }

    mutating func getUserWorkspace(base: String, completed: @escaping () -> ()){
        let url = URL(string: "some url")!
        var request = URLRequest(url: url)

        request.addValue("Basic \(base)", forHTTPHeaderField: "Authorization")
        request.addValue("application/json", forHTTPHeaderField: "Accept")

        URLSession.shared.dataTask(with: request){ (data, response, error) in
            if error == nil {
                do {
                    let res: Workspace = try JSONDecoder().decode(Workspace.self, from: data!)
                    Workspace.shared.guid = res.guid  //Error here
                    Workspace.shared.name = res.name  //Error here
                    DispatchQueue.main.async {
                        completed()
                    }
                }catch {
                    print ("JSON error")
                }
            }
            }.resume()
    }
}

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