Swift：不符合协议NSCoding

问题描述：

我正在尝试在我用swift编写的类上使用NSCoding协议，但似乎无法弄清楚为什么编译器在我实现所需方法时抱怨它不符合协议NSCoding：

I am trying to use the NSCoding protocol on a class I have written in swift, but cannot seem to figure out why the compiler complains that it "does not conform to protocol NSCoding" when I do implement the required methods:

class ServerInfo: NSObject, NSCoding {

    var username = ""
    var password = ""
    var domain = ""
    var location = ""
    var serverFQDN = ""
    var serverID = ""

    override init() {

    }

    init(coder aDecoder: NSCoder!) {
        self.username = aDecoder.decodeObjectForKey("username") as NSString
        self.password = aDecoder.decodeObjectForKey("password") as NSString
        self.domain = aDecoder.decodeObjectForKey("domain") as NSString
        self.location = aDecoder.decodeObjectForKey("location") as NSString
        self.serverFQDN = aDecoder.decodeObjectForKey("serverFQDN") as NSString
        self.serverID = aDecoder.decodeObjectForKey("serverID") as NSString
    }


    func encodeWithCoder(_aCoder: NSCoder!) {
        _aCoder.encodeObject(self.username, forKey: "username")
        _aCoder.encodeObject(self.password, forKey: "password")
        _aCoder.encodeObject(self.domain, forKey: "domain")
        _aCoder.encodeObject(self.location, forKey: "location")
        _aCoder.encodeObject(self.serverFQDN, forKey: "serverFQDN")
        _aCoder.encodeObject(self.serverID, forKey: "serverID")
    }

}

这是一个错误还是我错过了什么？

Is this a bug or am I just missing something?

答

正如您在报告导航器中的详细编译器消息中所看到的，
您的方法未正确声明：

As you can see in the detailed compiler messages in the Report navigator, your methods are not declared correctly:


error: type 'ServerInfo' does not conform to protocol 'NSCoding'
class ServerInfo: NSObject, NSCoding {
^
Foundation.NSCoding:2:32: note: protocol requires function 'encodeWithCoder' with type '(NSCoder) -> Void'
  @objc(encodeWithCoder:) func encodeWithCoder(aCoder: NSCoder)
                               ^
note: candidate has non-matching type '(NSCoder!) -> ()'
    func encodeWithCoder(_aCoder: NSCoder!) {
         ^
Foundation.NSCoding:3:25: note: protocol requires initializer 'init(coder:)' with type '(coder: NSCoder)'
  @objc(initWithCoder:) init(coder aDecoder: NSCoder)
                        ^
note: candidate has non-matching type '(coder: NSCoder!)'
    init(coder aDecoder: NSCoder!) {

（这可能在beta版本之间发生了变化。）
此外， initWithCoder 方法必须标记为 required ：

(This may have changed between the beta releases.) In addition, the initWithCoder method has to be marked as required:

required init(coder aDecoder: NSCoder) {   }

func encodeWithCoder(_aCoder: NSCoder) {   }

在 Swift 3 ong>所需的方法是

required init(coder aDecoder: NSCoder) {   }

func encode(with aCoder: NSCoder) {   }

Swift：不符合协议NSCoding

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