Swift中的lazy属性相当于Objective C中的lazy Init getter [英] lazy attribute in Swift equivalent to lazy Init getter in Objective C

问题描述

Swift中的lazy属性是否相当于在Objective C中使用延迟加载模式覆盖getter？

Is the lazy attribute in Swift equivalent to overriding the getter with a lazy loading pattern in Objective C?

推荐答案

来自文档：

惰性存储属性是一个属性，其初始值在第一次使用之前不会计算。你通过在声明之前写入lazy属性来表示一个惰性存储属性。

A lazy stored property is a property whose initial value is not calculated until the first time it is used. You indicate a lazy stored property by writing the lazy attribute before its declaration.

所以，大多数情况下是的。

So, mostly, yes.

您必须始终将惰性属性声明为变量（使用var关键字），因为在实例初始化完成之后才可能检索其初始值。常量属性在初始化完成之前必须始终具有值，因此不能声明为惰性。

You must always declare a lazy property as a variable (with the var keyword), because its initial value may not be retrieved until after instance initialization completes. Constant properties must always have a value before initialization completes, and therefore cannot be declared as lazy."

请记住，在Swift上你有为您的属性声明自定义getter和setter的选项：

Remember that on Swift you have the option to declare custom getters and setters for your properties:

var name : String?{
  get{
    return "Oscar"
  }
  set(newValue){

  }
}

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