swift学习笔记--按钮样式

1 需求

屏幕背景设置为纯黑色，底部一排放几个按钮。按钮黑底白字白色边框，当点击按钮后，按钮变为白底黑字。

2 实现

很简单的需求，不过UIVIewController直接设置backgroundColor无效，需要定义一个UIView放上去，然后在UIView上加按钮即可。代码如下：

    override func viewDidLoad() {
        super.viewDidLoad()
        wid = view.bounds.width
        hei = view.bounds.height
        // 直接设置view的backgroundColor不生效
        myView = UIView(frame: CGRect(x: 0, y: 0, width: wid, height: hei))
        myView.backgroundColor = UIColor.black
        view.addSubview(myView)
        // 底部按钮设置
        setBottomBtn()
    }
    func setBottomBtn() {
        let btnWid:CGFloat = (wid - 20*6)/5
        let btnY:CGFloat = hei - btnX - btnHei
        let btnNameArr = ["测试", "自强", "弘毅", "求是", "拓新"]
        for i in 0..<btnNameArr.count {
            let btn = UIButton(frame: CGRect(x: btnX*CGFloat(i+1) + btnWid*CGFloat(i), y: btnY, width: btnWid, height: btnHei))
            decorateBtn(btn: btn, title: btnNameArr[i])
            myView.addSubview(btn)
            btn.addTarget(self, action: #selector(bottomBtnTap(btn:)), for: .touchUpInside)
        }
    }
    @objc func bottomBtnTap(btn: UIButton) {
        // 点击变化颜色
        btn.setTitleColor(UIColor.black, for: .normal)
        btn.backgroundColor = UIColor.white
    }
    
    // 给btn加样式
    func decorateBtn(btn: UIButton, title: String) {
        btn.setTitleColor(UIColor.white, for: .normal) // 按钮上文字颜色
        btn.setTitle(title, for: .normal)
        btn.contentHorizontalAlignment = .center
        //btn1.backgroundColor = UIColor.blue             // 按钮背景色
        btn.layer.cornerRadius = 5    // 圆角
        btn.clipsToBounds = true;
        // 边框及颜色
        btn.layer.borderWidth = 1;
        btn.layer.borderColor = UIColor.white.cgColor
    }