IOS design model learning (10) Appearance

1 Preface
In many old object-oriented applications, many classes may be scattered in systems with various functions. To use these classes for a function, you need to know all the details before using them in a group of algorithms. If some classes are logically combined into a simplified interface, these classes can be easier to use. One way to provide unified interfaces for subsystems to satisfy different interfaces becomes the appearance mode.

2. Details
2.1 Brief Introduction
The appearance mode provides unified interfaces for subsystems to satisfy different interfaces. The upper-layer interfaces are defined. by reducing complexity and hiding the communication and dependency between subsystems, the subsystems are easier to use.

The appearance defines a high-level interface to make the subsystem easier to use.

2.2 When to use the appearance Mode
(1) subsystems are gradually becoming complicated. Many classes are produced during the application model process. You can use the appearance to provide a simple interface for these sub-system classes.

(2) You can use the appearance to layer the subsystem. Each subsystem level has an appearance as the entry point. Allowing them to communicate with each other through their appearance can simplify their dependencies.

3 conclusion
The above is all content and I hope it will help you.