Question

我需要向现有类动态添加属性，然后访问它们。我发现this answer是使用objc_setAssociatedObject的，但没有关于如何使用它的上下文。我该如何实现？

let dict = ["orderId":"abc", "postId+0":"zero", "postId+1":"one", "postId+2":"two"] // postIds can go on

let order = Order(dict: dict)
let dynamicProperties = order.accessDynamicProperties()
print(dynamicProperties)

班级：

class Order {

    var orderId: String?

    // I have a main initilizer that I use for something else that's why I'm using a convenience init
    convenience init(dict: [String: Any]) {
        self.init()

        orderId = dict["orderId"] as? String

        dynamicallyCreateProperties(dict: dict)
    }

    func dynamicallyCreateProperties(dict: [String: Any]) {

        for (key, value) in dict {

            if key.contains("+") {

               // dynamically add property and value to class
            }
        }
     }

     // returns something???
     func accessDynamicProperties() -> ??? {

     }
}

Answer 1

在评论中使用@DonMag的建议，他给了我一个很好的选择。他建议我创建一个字典作为类的一个属性，然后向其中添加键，值对。

class Order {

    var orderId: String?

    var dynamicDict = [String: Any]()

    convenience init(dict: [String: Any]) {
        self.init()

        orderId = dict["orderId"] as? String

        createDynamicKeyValues(dict: dict)
    }

    func createDynamicKeyValues(dict: [String: Any]) {

        for (key, value) in dict {

            if key.contains("+") {

                dynamicDict.updateValue(value, forKey: key)
            }
        }
    }
}

要使用它：

let dict = ["orderId":"abc", "postId+0":"zero", "postId+1":"one", "postId+2":"two"] // postIds can go on

let order = Order(dict: dict)

for (key, value) in order.dynamicDict {
    print(key)
    print(value)
}

Swift iOS-如何动态地向现有类添加属性然后访问它们

1 个答案: