Design Patterns
A design pattern solves a common software engineering problem. Patterns are abstract designs, not code. When you adopt a design, you adapt the general pattern to your specific needs.
设计模式解决了一个通用的软件工程问题。 模式是抽象的设计，不是代码。当你采用一个模式，就是让通用模式适应你的特殊需求。
No matter what type of app you are creating, you should know the fundamental design patterns used in the frameworks. Understanding design patterns helps you use frameworks more effectively and allows you to write programs that are more reusable, more extensible, and easier to change.
如论你创建的应用程序是什么类型的，你都需要了解框架里的基本设计模式。理解设计模式帮助你更有效地使用框架，并允许你编写更可重用，更可扩展，以及能更简单对其作出修改的程序。
Read This Article Now: Streamline Your App with Design Patterns describes the key design patterns and explains how these are used in app development. These design patterns are essentially the same for OS X and iOS.现在开始阅读文章：Streamline Your App with Design Patterns ，该文章描述了主要设计模式，并解释了在应用开发中如何使用它们。 这些设计模式在OS X 和 iOS里都通用。