主要学习的内容：
- 使用Segmented Control来切换视图
- 自定义Navigation Bar内容
- 自定义Search Bar
- 自定义UISearchController
开发环境：
- macOS 10.12
- Xcode 8.2
- iOS 10.2
- Swift 3.0
参考：
- Segmented Control Tutorial
- Show keyboard automatically when UISearchController is loaded
- Swift addsubview and remove it
- UISearchController: show results even when search bar is empty
- Swift UIView background color opacity
- How to change background color of UiSearchBar to black -SWIFT
- How can I change the UISearchBar search text color?
源代码：