swift4.0 项目中的随机校验码（验证码）

在开发中注册的时候移动端要求我们获取随机校码

完整代码

class CodeView: UIView {    var changeString:String?  //验证码的字符串    let kLineCount = 6    let kLineWidth = CGFloat(2.0)    let kCharCount = 4    let kFontSize = UIFont.systemFont(ofSize:(CGFloat(arc4random() % 5) + 18))    override init(frame: CGRect) {        super.init(frame: frame)        let randomColor:UIColor = UIColor(red: CGFloat(CGFloat(arc4random())/CGFloat(RAND_MAX)), green: CGFloat(CGFloat(arc4random())/CGFloat(RAND_MAX)), blue: CGFloat(CGFloat(arc4random())/CGFloat(RAND_MAX)), alpha: 0.5)//        self.layer.cornerRadius = 5.0   //设置layer圆角半径//        self.layer.masksToBounds = true //隐藏边界        self.backgroundColor = randomColor        getChangeCode()    }    required init?(coder aDecoder: NSCoder) {        fatalError("init(coder:) has not been implemented")    }    func getChangeCode()    {        //字符素材数组        let changeArray:NSArray = ["0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z","A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z"]        changeString = ""        //随机从数组中选取需要个数的字符，然后拼接为一个字符串        for _ in 0 ..< kCharCount {            let index = Int(arc4random())%(changeArray.count - 1)            let getStr = changeArray.object(at: index)            changeString = changeString! + (getStr as! String)        }    }    //触摸    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {        super.touchesBegan(touches, with: event)        getChangeCode()        setNeedsDisplay()    }    //画图    override func draw(_ rect: CGRect) {        super.draw(rect)        let randomBackColor = UIColor(red: CGFloat(CGFloat(arc4random())/CGFloat(RAND_MAX)), green: CGFloat(CGFloat(arc4random())/CGFloat(RAND_MAX)), blue: CGFloat(CGFloat(arc4random())/CGFloat(RAND_MAX)), alpha: 1.0)        self.backgroundColor = randomBackColor        //获得要显示验证码字符串，根据长度，计算每个字符显示的大概位置        let str = NSString(string: "S")        //        let font = UIFont.systemFontOfSize(20)        let size = str.size(withAttributes: ([NSAttributedStringKey.font : kFontSize]))        let width:CGFloat = rect.size.width / CGFloat(NSString(string: changeString!).length) - size.width        let height = rect.size.height - size.height        var point:CGPoint?        var pX:CGFloat?        var pY:CGFloat?        let stringCount:Int = (changeString?.characters.count)!        for i in 0 ..< stringCount {            pX = CGFloat(arc4random()).truncatingRemainder(dividingBy: width) + rect.size.width / CGFloat(NSString(string: changeString!).length)*CGFloat(i)            pY = CGFloat(arc4random()).truncatingRemainder(dividingBy: height)            point = CGPoint(x:pX!, y:pY!)            let c = NSString(string: changeString!).character(at: i)            let codeText:NSString? = NSString(format: "%C",c)            codeText!.draw(at: point!, withAttributes:  [NSAttributedStringKey.font : kFontSize])        }        //调用drawRect：之前，系统会向栈中压入一个CGContextRef，调用UIGraphicsGetCurrentContext()会取栈顶的CGContextRef        let context :CGContext = UIGraphicsGetCurrentContext()!        //设置画线宽度        context.setLineWidth(kLineWidth)        for _ in 0 ..< kLineCount {            //绘制干扰的彩色直线            let randomLineColor = UIColor(red: CGFloat(CGFloat(arc4random())/CGFloat(RAND_MAX)), green: CGFloat(CGFloat(arc4random())/CGFloat(RAND_MAX)), blue: CGFloat(CGFloat(arc4random())/CGFloat(RAND_MAX)), alpha: 0.5)            context.setStrokeColor(randomLineColor.cgColor)            //设置线的起点            pX = CGFloat(arc4random()).truncatingRemainder(dividingBy: rect.size.width)            pY = CGFloat(arc4random()).truncatingRemainder(dividingBy: rect.size.height)            context.move(to: CGPoint(x:pX!, y:pY!))            //设置线终点            pX = CGFloat(arc4random()).truncatingRemainder(dividingBy: rect.size.width)            pY = CGFloat(arc4random()).truncatingRemainder(dividingBy: rect.size.height)            context.addLine(to: CGPoint(x:pX!, y:pY!))            //画线            context.strokePath()        }    }    /*    // Only override draw() if you perform custom drawing.    // An empty implementation adversely affects performance during animation.    override func draw(_ rect: CGRect) {        // Drawing code    }    */}