ios - KVC 合规性 - 声明 iVar 的指南

Question

我已经看到支持以 2 种通用格式（在各种书籍、博客等中）声明的属性的ivars ：

myProperty = _myProperty;
myProperty = myProperty_; 

苹果文档说，前一个是关键值合规所必需的

哪一个最合适？

Answer 1

If you're creating a property, the name of the underlying ivar doesn't make any difference to KVC — it will go through the accessor. It will only access the instance variable if both of the following are true:

• It can't find any appropriate accessor for the key

• The object's class returns YES for accessInstanceVariablesDirectly

Answer 2

Apple 目前的非正式建议是使用下划线前缀。有迹象表明，将来会有语法上的便利。