设置三个按钮等宽分布

效果图：

思路：(self为自定义的View，里面有三个按钮和两个分隔线)

一、按钮约束：使三个按钮等宽分布

1、按钮一：上、左、下和self对齐，宽和“按钮二”对齐

2、按钮二：上、下和self对齐，宽和“按钮三”对齐，左和“按钮二”右对齐

3、按钮三：上、右、下和self对齐，左和“按钮二”右对齐

二、竖线约束：

1、分隔线一：CenterY和self对齐，CenterX和“按钮一”右对齐

2、分隔线二：CenterY和self对齐，CenterX和“按钮二”右对齐

 1 private func setupUI(){
 2         // 添加三个按钮
 3         let retweetButton = addChildButton(imageName: "timeline_icon_retweet",title: "转发")
 4         let commentButton = addChildButton(imageName: "timeline_icon_comment",title: "评论")
 5         let unlikeButton = addChildButton(imageName: "timeline_icon_unlike",title: "赞")
 6         
 7         // 添加两个分隔线
 8         let firstLineView = addChildLineView()
 9         let secondLineView = addChildLineView()
10         
11         // 设置三个按钮的约束
12         retweetButton.snp_makeConstraints { (make) in
13             make.top.leading.bottom.equalTo(self)
14             make.width.equalTo(commentButton)
15         }
16         commentButton.snp_makeConstraints { (make) in
17             make.top.bottom.equalTo(self)
18             make.leading.equalTo(retweetButton.snp_trailing)
19             make.width.equalTo(unlikeButton)
20         }
21         unlikeButton.snp_makeConstraints { (make) in
22             make.top.trailing.bottom.equalTo(self)
23             make.leading.equalTo(commentButton.snp_trailing)
24         }
25         
26         // 设置两个分隔线约束
27         firstLineView.snp_makeConstraints { (make) in
28             make.centerX.equalTo(retweetButton.snp_trailing)
29             make.centerY.equalTo(self)
30         }
31         secondLineView.snp_makeConstraints { (make) in
32             make.centerX.equalTo(commentButton.snp_trailing)
33             make.centerY.equalTo(self)
34         }
35     }
36     
37     // 创建button按钮
38     private func addChildButton(imageName:String,title:String) -> UIButton{
39         let button = UIButton()
40         button.setImage(UIImage(named:imageName), for: .normal)
41         button.setTitle(title, for: .normal)
42         button.titleLabel?.font = UIFont.systemFont(ofSize: 14)
43         button.setTitleColor(UIColor.darkGray, for: .normal)
44         button.setBackgroundImage(UIImage(named:"timeline_card_bottom_background"), for: .normal)
45         button.adjustsImageWhenHighlighted = false
46         addSubview(button)
47         return button
48     }
49     
50     // 创建竖线视图
51     private func addChildLineView() -> UIImageView{
52         let imageView = UIImageView(image:UIImage(named:"timeline_card_bottom_line"))
53         addSubview(imageView)
54         return imageView
55     }