UIBarButtonItem继承于UIBarItem，用于设置导航栏上的按钮组。

1.显示与隐藏回退按钮

1. self.navigationItem.hidesBackButton = true
2. self.navigationItem.setHidesBackButton(true, animated: true)

2.创建文字按钮

1. //左侧按钮
2. let leftButton = UIBarButtonItem(title: “Back”, style: .plain, target: self, action: #selector(FirstPageViewController.prevButton))
3. self.navigationItem.leftBarButtonItem = leftButton
5. //右侧按钮
6. let rightButton = UIBarButtonItem(title: “Next”, style: .plain, target: self, action: #selector(FirstPageViewController.nextButton))
7. self.navigationItem.rightBarButtonItem = rightButton

3.创建系统自带按钮

1. let addButton = UIBarButtonItem(barButtonSystemItem: .add, target: self, action: nil)
2. let cameraButton = UIBarButtonItem(barButtonSystemItem: .camera, target: self, action: nil)
3. let editButton = UIBarButtonItem(barButtonSystemItem: .edit, target: self, action: nil)
5. //同时添加多个按钮
6. self.navigationItem.rightBarButtonItems = [addButton,cameraButton,editButton]

4.添加自定义按钮

1. //自定义搜索框
2. let search = UITextField(frame: CGRect(x: 0, y: 0, width: 200, height: 25))
3. search.backgroundColor = UIColor.gray
4. search.placeholder = “请输入搜索内容”
5. search.layer.masksToBounds = true
6. search.layer.cornerRadius = 8
7. search.layer.borderWidth = 2
8. search.layer.borderColor = UIColor.blue.cgColor
9. let itemButton = UIBarButtonItem(customView: search)
11. //文本
12. let txt = UILabel(frame: CGRect(x: 0, y: 0, width: 40, height: 25))
13. txt.text = “搜索”
14. let txtButton = UIBarButtonItem(customView: txt)
16. //添加按钮组
17. self.navigationItem.rightBarButtonItems = [itemButton, txtButton]

5.按钮样式

1. let leftButton = UIBarButtonItem(title: “Back”, style: .plain, target: self, action: #selector(FirstPageViewController.prevButton))
2. //字体颜色
3. leftButton.tintColor = UIColor.red
4. //按钮背景图片
5. leftButton.setBackgroundImage(UIImage(named:“image”), for: .normal, barMetrics: .default)
7. self.navigationItem.leftBarButtonItem = leftButton

效果如下图: