UIBezierPath贝塞尔曲线

import UIKit

class ViewController: UIViewController {

    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let viewRect = CGRect(x: 0, y: 0, width: 400, height: 400)
        let view1 = MyView(frame: viewRect)
        self.view.addSubview(view1)
    }
    
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
}
class MyView: UIView {
    
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        self.backgroundColor = UIColor.clearColor()
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    override func drawRect(rect: CGRect) {
        super.drawRect(rect)
        
        let path = UIBezierPath()
        path.lineWidth = 1//路径宽度
        path.lineCapStyle = .Round//端点样式(枚举)
        path.lineJoinStyle = .Round//连接点样式(枚举)
        path.moveToPoint(CGPoint(x:200,y:50))//设置起点
        path.addLineToPoint(CGPoint(x:300,y:100))//从上一点连接一条线到本次指定的点
        path.addLineToPoint(CGPoint(x:260,y:200))
        path.addLineToPoint(CGPoint(x:100,y:200))
        path.addLineToPoint(CGPoint(x:100,y:70))
        path.closePath()//闭合路径，把起始点和终点连接起来
        UIColor.blueColor().setFill()//设置填充颜色(不常用
        UIColor.redColor().setStroke()//设置路径颜色(不常用)
        path.fill()
        path.stroke()
        
        
    }


}

画圆

/*
  参数解释：
  1.center: CGPoint  中心点坐标
  2.radius: CGFloat  半径
  3.startAngle: CGFloat 起始点所在弧度
  4.endAngle: CGFloat   结束点所在弧度
  5.clockwise: Bool     是否顺时针绘制
  7.画圆时，没有坐标这个概念，根据弧度来定位起始点和结束点位置。M_PI即是圆周率。画半圆即(0,M_PI),代表0到180度。全圆则是(0,M_PI*2)，代表0到360度
*/
let mainPath1 = UIBezierPath(arcCenter: CGPoint(x: 50, y: 50), radius: 50, startAngle: CGFloat(M_PI) * 0, endAngle: CGFloat(M_PI) * 2, clockwise: true)