摘要：Objects should have clearly-defined tasks, such as modeling specific information, displaying visual content or controlling the flow of information. As 阅读全文

摘要：The majority of work in an Objective-C application happens as a result of messages being sent back and forth across an ecosystem of objects. Some of t 阅读全文

摘要：When you write software for OS X or iOS, most of your time is spent working with objects. Objects in Objective-C are just like objects in other object 阅读全文

摘要：苹果Documentation Archive里面有很多值得反复阅读的经典文档。但是，可能由于有的文档组织有点乱，或者有的文档讲了一些苹果现在不太想让开发者知道的信息，苹果正在慢慢删除这些旧的文档。同时，阅读官方文档是全面学习一项技术的重要一环，所以备份在此。 文档中间我会标注重点，或加入一些自己的 阅读全文