Extension

enum DashedLineType {
    case All,Top,Down,Right,Left
}

extension UIView {
    // 点線・破線を描くメソッド
    func drawDashedLine(color: UIColor, lineWidth: CGFloat, lineSize: NSNumber, spaceSize: NSNumber, type: DashedLineType) {
        let dashedLineLayer: CAShapeLayer = CAShapeLayer()
        dashedLineLayer.frame = self.bounds
        dashedLineLayer.strokeColor = color.cgColor
        dashedLineLayer.lineWidth = lineWidth
        dashedLineLayer.lineDashPattern = [lineSize, spaceSize]
        let path: CGMutablePath = CGMutablePath()

        switch type {

        case .All:
            dashedLineLayer.fillColor = nil
            dashedLineLayer.path = UIBezierPath(rect: dashedLineLayer.frame).cgPath
        case .Top:
            path.move(to: CGPoint(x: 0.0, y: 0.0))
            path.addLine(to: CGPoint(x: self.frame.size.width, y: 0.0))
            dashedLineLayer.path = path
        case .Down:
            path.move(to: CGPoint(x: 0.0, y: self.frame.size.height))
            path.addLine(to: CGPoint(x: self.frame.size.width, y: self.frame.size.height))
            dashedLineLayer.path = path
        case .Right:
            path.move(to: CGPoint(x: self.frame.size.width, y: 0.0))
            path.addLine(to: CGPoint(x: self.frame.size.width, y: self.frame.size.height))
            dashedLineLayer.path = path
        case .Left:
            path.move(to: CGPoint(x: 0.0, y: 0.0))
            path.addLine(to: CGPoint(x: 0.0, y: self.frame.size.height))
            dashedLineLayer.path = path
        }
        self.layer.addSublayer(dashedLineLayer)
    }
}

使用方法

hogeView.drawDashedLine(UIColor.blueColor(), lineWidth: 2, lineSize: 3, spaceSize: 3, type: .All)