在面向对象程序里,一个对象不要直接访问另一个对象内部的数据。所以我们使用accessor methods来进行对象内部的数据交互。
accessor methods(getters and setters) are used as an abstraction for interacting with the object’s underlying data.
retain就是MRC版的strong
The retain
attribute is the Manual Retain Release version of strong
, and it has the exact same effect: claiming ownership of assigned values. You shouldn’t use this in an Automatic Reference Counted environment.
那么assign就是iOS5版本前的weak
The assign Attribute
The assign
attribute doesn’t perform any kind of memory-management call when assigning a new value to the property. This is the default behavior for primitive data types, and it used to be a way to implement weak references before iOS 5
时间: 2024-10-20 13:47:46