Question

有人能告诉我我的代码有什么问题吗？

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

对于较短的说明，我将SKSpriteNode替换为Any，因为您必须稍后更详细地处理指定的init() SKSpriteNode ..有关初始化程序要求的详细信息在协议中，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"

Answer 2

我目前的不完美解决方案。@FlorianWeßling

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

protocol SKSpriteNodeProtocol {
    var position: CGPoint {get set}
    var size: CGSize {get set}
    //or more properties you want
}

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

    var person: PersonType

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

extension SKSpriteNode : SKSpriteNodeProtocol {}

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

    required init(name: String) {
        personName = name
        super.init(texture: nil, color: UIColor.clearColor(), size: CGSizeZero)
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

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

Answer 3

如果访问unpivot中的SKSpriteNode非常重要，那么您可以添加一个简单变量NameCard并从node中移除继承：

SKSpriteNode

spriteKit的swift协议init func错误

3 个答案: