SpriteKit 的 swift 协议(protocol)初始化函数错误

Question

谁能告诉我我的代码有什么问题吗？

code in playground

error detail

protocol PersonWithName: class  {
    var personName: String {get set}

    init(name: String)
}

class NameCard<PersonType: SKSpriteNode where PersonType: PersonWithName> {

    var person: PersonType

    init() {
        self.person = PersonType(name: "No Name") // this line error.
    }
}

Answer 1

为了更简短的说明，我将 SKSpriteNode 替换为 Any，因为您必须处理 SKSpriteNode 的指定 init() code> 稍后会详细介绍。有关协议(protocol)中初始化程序要求的更多详细信息，请查看 this section of Apple's Developer Guide

protocol PersonWithName: class  {
    var personName: String {get set}
    init(name: String)
}

class NameCard<PersonType: Any where PersonType: PersonWithName> {

    var person: PersonType

    init() {
        self.person = PersonType(name: "No Name")
    }
}

class ExampleClass: PersonWithName {
    var personName: String = ""

    required init(name: String) {
        personName = name
    }
}

var test = NameCard<ExampleClass>()
print(test.person.personName) // "No Name"