swift 自定义 UIStepper

系统自带的UIStepper没有显示当前value值得控件，需要自行添加label来显示。而此控件自带一个label来显示当前值。而且，与系统UIStepper的属性一样都可以设置的。
控件类型分为普通类型，以及外层带有圆圈的。在这里，左边的减号，右边的加号，以及当类型为circle时的圆圈是通过CAShapeLayer和UIBezierPath画出来的，非UIButton控件。

/**
 控件类型
 
 - custome: 默认
 - circle:  外层带圆圈
 */
enum StepType {
    case custom
    case circle
}


控件的初始化方法，可选择闭包处理点击事件，或者选择代理

/**
     初始化方法
     
     - parameter frame: 控件frame--若想circle类型时，成圆形，最好宽高比为10:3
     - parameter type:  控件类型
     - action: 点击闭包，可选代理或者闭包，二选1
     
     - returns: 此控件
     */
    init(frame: CGRect, type: StepType, action: TypeClouse?) {
        self.stepType = type
        self.action = action
        super.init(frame: frame)
        defaultAppearance()
    }

控件有个属性，是设置控件外观的。里面有个属性观察器didSet方法---当设置外观的时候调用draw()方法~~~
此方法，先reset UI--即清除UI上所有的控件以及layer，然后在重新布置界面---如果不设置的话，会使用默认设置

var appearance: Appearance! {
        didSet {
            self.draw()
        }
    }

private func reset() {
    //清除控件
        for sub in subviews {
            sub.removeFromSuperview()
        }
//清除layer
        if let layers = layer.sublayers {
            for lay in layers {
                lay.removeFromSuperlayer()
            }
        }
    }
    
    private func draw() {
        reset()
        let centerY = frame.size.height * 0.5
        let width = frame.size.width
        let linePath = UIBezierPath()
        defer {
            linePath.closePath()
        }
        //(- : label : +) = (3:4:3)
        // 画减号
        //(空白:-:空白) = (3:4:3)
        //线条宽度/高度
        let lineHeight = frame.size.height / 3
        // 减号起始点
        let startX1 = width * 0.3 * 0.3
        linePath.moveToPoint(CGPoint(x: startX1, y: centerY))
        linePath.addLineToPoint(CGPoint(x: startX1 + lineHeight, y: centerY))
        // 画加号
        //(空白:+:空白) = (3:4:3)
        //横线
        // 加号起始点
        let startX2 = width - width * 0.3 * 0.3 - lineHeight
        linePath.moveToPoint(CGPoint(x: startX2, y: centerY))
        linePath.addLineToPoint(CGPoint(x: startX2 + lineHeight, y: centerY))
        //竖线
        linePath.moveToPoint(CGPoint(x: startX2 + lineHeight * 0.5, y: centerY - lineHeight * 0.5))
        linePath.addLineToPoint(CGPoint(x: startX2 + lineHeight * 0.5, y: centerY + lineHeight * 0.5))
        
        let lineLayer = CAShapeLayer()
        lineLayer.path = linePath.CGPath
        lineLayer.strokeColor = appearance.actionColor.CGColor
        lineLayer.lineWidth = 1
        self.layer.addSublayer(lineLayer)
        
        let (leftFrame, remainFrame) = bounds.divide(bounds.size.width * 0.3, fromEdge: .MinXEdge)
        let (middleFrame, rightFrame) = remainFrame.divide(remainFrame.size.width * 4 / 7, fromEdge: .MinXEdge)
 
        label.frame = middleFrame
        addSubview(label)
        label.textAlignment = .Center
        label.textColor = appearance.textColor
        label.font = appearance.textFont
        label.adjustsFontSizeToFitWidth = true
        
        //添加action
        let reduceC = UIControl(frame: leftFrame)
        reduceC.addTarget(self, action: #selector(reduce), forControlEvents: .TouchUpInside)
        addSubview(reduceC)
        
        let addC = UIControl(frame: rightFrame)
        addC.addTarget(self, action: #selector(add), forControlEvents: .TouchUpInside)
        addSubview(addC)
        
        switch stepType {
        case .circle:
            let scale: CGFloat = 0.7
            let reduceFrame = CGRect(x: leftFrame.size.width * 0.5 * (1 - scale), y: centerY - leftFrame.size.height * scale * 0.5, width: leftFrame.size.width * scale, height: leftFrame.size.height * scale)
            let reducePath = UIBezierPath(ovalInRect: reduceFrame)
            let reduceLayer = CAShapeLayer()
            reduceLayer.path = reducePath.CGPath
            reduceLayer.fillColor = appearance.fillColor.CGColor
            reduceLayer.strokeColor = appearance.strokeColor.CGColor
            reduceLayer.lineWidth = 1
            layer.addSublayer(reduceLayer)
            
            let addFrame = CGRect(x: startX2 + lineHeight * 0.5 - rightFrame.size.width * scale * 0.5, y: centerY - rightFrame.size.height * scale * 0.5, width: rightFrame.size.width * scale, height: rightFrame.size.height * scale)
            let addPath = UIBezierPath(ovalInRect: addFrame)
            let addLayer = CAShapeLayer()
            addLayer.path = addPath.CGPath
            addLayer.fillColor = appearance.fillColor.CGColor
            addLayer.strokeColor = appearance.strokeColor.CGColor
            addLayer.lineWidth = 1
            layer.addSublayer(addLayer)
        case .custom:
            return
        }
    }

外界调用代码：

stepV = ZGJStepView(frame: CGRect(x: 50, y: 400, width: 300, height: 90), type: .custom, action: nil)
        
        stepV.backgroundColor = UIColor.lightGrayColor()
        stepV.minimumValue = 2
        stepV.maximumValue = 10
        stepV.stepValue = 1
        stepV.delegate = self
        stepV.appearance = Appearance(
            actionColor: UIColor.redColor(),
            strokeColor: UIColor.redColor(),
            fillColor: UIColor.clearColor(),
            textColor: UIColor.blackColor(),
            textFont: UIFont.systemFontOfSize(15))
        view.addSubview(stepV)

下面是控件一些可设置的属性，与系统UIStepper的属性非常相识，可以无痛转接

/// 最小值  默认0
    var minimumValue: Double = 0 {
        didSet {
            self.value = minimumValue
            if minimumValue % 1.0 == 0.0 {
              label.text = "\(Int(minimumValue))"
            } else {
              label.text = "\(minimumValue)"
            }
        }
    }
    /// 最大值默认 100
    var maximumValue: Double = 100
    /// 每一次点击增减值 默认1
    var stepValue: Double = 1
    /// 当前值---默认0
    var value: Double = 0 {
        didSet {
            if stepValue % 1.0 == 0.0 && minimumValue % 1.0 == 0.0 {
                label.text = "\(Int(value))"
            } else {
                label.text = "\(value)"
            }
        }
    }

然后是可以设置控件的外观

/**
 *  控件的基本设置
 */
struct Appearance {
    /// ➕/➖的颜色
    var actionColor: UIColor
    /// circle类型时，外围圆圈颜色
    var strokeColor: UIColor
    var fillColor: UIColor
    /// 字体颜色
    var textColor: UIColor
    /// 字体
    var textFont: UIFont
}

git地址：https://github.com/guijie20140501/ZGJStepView.git