swift - NSCopying类

Question

在Swift 2.1中，我应该如何创建符合NSCopying协议的类？

我试过了：

class TargetValue: NSObject, NSCopying {

    var value: Int?

    func copyWithZone(zone: NSZone) -> AnyObject {
        let copy = TargetValue()
        copy.value = value
        return copy
    }
}

var target = TargetValue()
target.value = 12

var target1 = target.copy()
print(target1.value ) // ambiguous user of 'value'

但是我遇到了ambiguous user of value的错误。我该怎么做才能解决这个问题？

此致

Answer 1

copyWithZone:返回AnyObject，因此您必须将副本转换为预期类型：

var target1 = target.copy() as! TargetValue