private var middleNameKey :Void?
extension User {
var middleName :String? {
get{
return objc_getAssociatedObject(self, &middleNameKey) as? String
}
set{
objc_setAssociatedObject(self, &middleNameKey, newValue, .OBJC_ASSOCIATION_COPY_NONATOMIC)
}
}
}
使用
let user =User()
user.middleName="jake"
print(user.middleName)











网友评论