1. UIBezierPath： UIBezierPath是在 UIKit 中的一个类，继承于NSObject,可以创建基于矢量的路径.此类是Core Graphics框架关于path的一个OC封装。使用此类可以定义常见的圆形、多边形等形状 。我们使用直线、弧（arc）来创建复杂的曲线形状。每一个直线段或者曲线段的结束的地方是下一个的开始的地方。每一个连接的直线或者曲线段的集合成为subpath。一个UIBezierPath对象定义一个完整的路径包括一个或者多个subpaths。
2. CAShapeLayer： 继承于CALayer。 每个CAShapeLayer对象都代表着将要被渲染到屏幕上的一个任意的形状(shape)。具体的形状由其path(类型为CGPathRef)属性指定。 普通的CALayer是矩形，所以需要frame属性。CAShapeLayer它本身没有形状，它的形状来源于其属性path 。CAShapeLayer有不同于CALayer的属性，它从CALayer继承而来的属性在绘制时是不起作用的。

具体用法看代码

仅仅使用UIBezierPath来绘图的话，需要在view的drawRect方法里实现,详细可以看MyView的drawRect方法

//
//  MyView.m
//  CAShapeLayerAndUIBezierPath
//
//  Created by 蔡欣东 on 16/4/21.
//  Copyright © 2016年 蔡欣东. All rights reserved.
//

#import "MyView.h"

@implementation MyView

- (void)drawRect:(CGRect)rect {
    [self simpleDraw];
    [self drawARCPath];
    [self drawTrianglePath];
    [self drawSecondBezierPath];
}

//画圆角矩形
-(void)simpleDraw{
    UIBezierPath* path = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(20, 20, 100, 100) cornerRadius:20];
    path.lineWidth = 5;

    //设置填充颜色
    UIColor* fillColor = [UIColor greenColor];
    [fillColor set];
    [path fill];

    //设置线的颜色，需要在填充颜色之后设置
    UIColor* lineColor = [UIColor redColor];
    [lineColor set];
    [path stroke];
}


//画圆弧
-(void)drawARCPath{
    UIBezierPath* path = [UIBezierPath bezierPathWithArcCenter:CGPointMake(20, 150) radius:100 startAngle:0 endAngle:M_PI*90/180 clockwise:YES];

    //连接处的样式
    path.lineCapStyle = kCGLineCapRound;
    //连接方式
    path.lineJoinStyle = kCGLineJoinRound;
    path.lineWidth = 5;

    UIColor* lineColor = [UIColor redColor];
    [lineColor set];
    [path stroke];
}

//画三角形
-(void)drawTrianglePath{
    UIBezierPath* path = [UIBezierPath bezierPath];
    //设置起点
    [path moveToPoint:CGPointMake(20, 300)];
    [path addLineToPoint:CGPointMake(150, 400)];
    [path addLineToPoint:CGPointMake(20, 400)];
    [path closePath];

    path.lineWidth = 5;

    UIColor* fillColor = [UIColor greenColor];
    [fillColor set];
    [path fill];

    UIColor* lineColor = [UIColor redColor];
    [lineColor set];
    [path stroke];


}

//画二次贝尔曲线
-(void)drawSecondBezierPath{
    UIBezierPath* path = [UIBezierPath bezierPath];
    [path moveToPoint:CGPointMake(200, 150)];
    [path addQuadCurveToPoint:CGPointMake(200, 300) controlPoint:CGPointMake(50, 50)];
    path.lineWidth = 5;

    UIColor* lineColor = [UIColor redColor];
    [lineColor set];
    [path stroke];
}

@end

用CAShapeLayer和UIBezierPath画图，以及结合CAAnimation实现一个绘图动画

动画效果：

gif1.gif

//
//  ViewController.m
//  CAShapeLayerAndUIBezierPath
//
//  Created by 蔡欣东 on 16/4/21.
//  Copyright © 2016年 蔡欣东. All rights reserved.
//

#import "ViewController.h"
#import "MyView.h"
@interface ViewController (){
    CAShapeLayer *layer;
}

@end


@implementation ViewController


- (void)viewDidLoad {
    [super viewDidLoad];

    //仅仅使用UIBezierPath的话，需要在view的drawRect方法里实现,详细可以看MyView的drawRect方法
//    CGFloat W = [UIScreen mainScreen].bounds.size.width;
//    CGFloat H = [UIScreen mainScreen].bounds.size.height;
//    MyView* myView = [[MyView alloc]initWithFrame:CGRectMake(0, 0, W, H)];
//    myView.backgroundColor = [UIColor whiteColor];
//    [self.view addSubview:myView];




    //CAShapeLayer和UIBezierPath画图

    layer = [CAShapeLayer layer];
    layer.fillColor = [UIColor clearColor].CGColor;
    layer.lineWidth =  20.0f;
    layer.lineCap = kCALineCapRound;
    layer.lineJoin = kCALineJoinRound;
    layer.strokeColor = [UIColor redColor].CGColor;
    [self.view.layer addSublayer:layer];

    // 创建贝塞尔路径
    UIBezierPath *path = [UIBezierPath bezierPathWithArcCenter:CGPointMake(200, 200) radius:80 startAngle:0 endAngle:M_PI*2 clockwise:NO];


    // 关联layer和贝塞尔路径
    layer.path = path.CGPath;

    // 创建Animation
    CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"strokeEnd"];
    animation.fromValue = @(0.0);
    animation.toValue = @(1.0);
    layer.autoreverses = NO;
    animation.duration = 3.0;

    // 设置layer的animation
    [layer addAnimation:animation forKey:nil];
    animation.delegate = self;


    int count = 16;
    for (int i = 0; i<count; i++) {
        CAShapeLayer* lineLayer = [CAShapeLayer layer];
        lineLayer.fillColor = [UIColor clearColor].CGColor;
        lineLayer.strokeColor = [UIColor yellowColor].CGColor;
        lineLayer.lineWidth = 15.0f;
        lineLayer.lineCap = kCALineCapRound;
        lineLayer.lineJoin = kCALineCapRound;
        [self.view.layer addSublayer:lineLayer];

        UIBezierPath* path2 = [UIBezierPath bezierPath];
        int x = 200+100*cos(2*M_PI/count*i);
        int y = 200-100*sin(2*M_PI/count*i);
        int len = 50;
        [path2 moveToPoint:CGPointMake(x, y)];
        [path2 addLineToPoint:CGPointMake(x+len*cos(2*M_PI/count*i), y-len*sin(2*M_PI/count*i))];
        lineLayer.path = path2.CGPath;
        [lineLayer addAnimation:animation forKey:nil];
    }

}

//animation结束回调
-(void)animationDidStop:(CAAnimation *)anim finished:(BOOL)flag{
    NSLog(@"yes");
    layer.fillColor = [UIColor redColor].CGColor;
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];

}

@end