Swift:将类型作为参数发送并将变量的类型与其进行比较

Question

我想实现这样一个功能:

protocol Base {
    var value: Int { get set }
}
class ObjectTypeA: Base {
    var value: Int = 0
}
class ObjectTypeB: Base {
    var value: Int = 1
}

var objects: [Base] = [ObjectTypeA(), ObjectTypeB()]
func updatePropertyForType(type: Base.Type, value: Int) {
    objects.filter({ $0 is type }).forEach { // <<< ERROR IS HERE
        var object = $0
        object.value = value
    }
}
updatePropertyForType(ObjectTypeB.self, value: 10)

但是有一个错误:

'type' is not a type

请帮我解决一下。

Answer 1

参见 this answer :

protocol Base: AnyObject {
    var value: Int { get set }
}
class ObjectTypeA: Base {
    var value: Int = 0
}
class ObjectTypeB: Base {
    var value: Int = 1
}

var objects: [Base] = [ObjectTypeA(), ObjectTypeB()]
func updatePropertyForType(type: Base.Type, value: Int) {
    objects.filter({let item = $0; return type === item.dynamicType }).forEach {
        $0.value = value
    }
}

调用它:

updatePropertyForType(ObjectTypeA.self, value: 3)