学步园

1. 创建一个path对象
2. 使用方法moveToPoint：设置初始线段的起点
3. 添加line或者curve定义一个或者多个subpaths
4. 添加UIBezierPath对象绘图的属性

简单代码如下：

    UIBezierPath *path=[UIBezierPath bezierPath];

    [path moveToPoint:CGPointMake(0, 0)];

    [path addLineToPoint:CGPointMake(60, 60)];

    [path addLineToPoint:CGPointMake(20, 20)];

    [path closePath];//关闭path，这个方法会自动连接最后点和起始点

画圆弧

    UIBezierPath *path=[UIBezierPath bezierPath];

    [path addArcWithCenter:CGPointMake(100, 100) radius:60 startAngle:0 endAngle:360clockwise:YES];

立方和二次贝塞尔曲线

例子：画一个圆圈，并且动画围绕圆圈绕一圈

#import "ViewController.h"

#import <QuartzCore/QuartzCore.h>

@interface ViewController ()

{

    CAShapeLayer *arcLayer;

}

@end

@implementation ViewController

- (void)viewDidLoad

{

    [super viewDidLoad];

    [self intiUIOfView];

    self.view.backgroundColor = [UIColor grayColor];

    NSTimer *timer = [NSTimer timerWithTimeInterval:3 target:self selector:@selector(dosometing:) userInfo:nil repeats:YES];

    [[NSRunLoop currentRunLoop] addTimer:timer forMode:NSDefaultRunLoopMode];

}

- (void)dosometing:(id)sender

{

    NSLog(@"dosometing");

    arcLayer.strokeColor = nil;

    [self drawLineAnimation:arcLayer];

     arcLayer.strokeColor=[UIColor colorWithWhite:1 alpha:0.7].CGColor;

}

-(void)intiUIOfView

{

    UIBezierPath *path=[UIBezierPath bezierPath];

    CGRect rect=[UIScreen mainScreen].applicationFrame;

    NSLog(@"width: %f ,height: %f",CGRectGetWidth(rect),CGRectGetHeight(rect));

    [path addArcWithCenter:CGPointMake(100,100) radius:100 startAngle:0 endAngle:2*M_PI clockwise:YES];

    arcLayer=[CAShapeLayer layer];

    arcLayer.path=path.CGPath; 

    arcLayer.fillColor=[UIColor redColor].CGColor;

    arcLayer.strokeColor=[UIColor colorWithWhite:1 alpha:0.7].CGColor;

    arcLayer.lineWidth=3;

    arcLayer.frame=self.view.frame;

    [self.view.layer addSublayer:arcLayer];

    [self drawLineAnimation:arcLayer];

}

-(void)drawLineAnimation:(CALayer*)layer

{

    CABasicAnimation *bas=[CABasicAnimation animationWithKeyPath:@"strokeEnd"];

    bas.duration=3;

    bas.delegate=self;

    bas.fromValue=[NSNumber numberWithInteger:0];

    bas.toValue=[NSNumber numberWithInteger:1];

    [layer addAnimation:bas forKey:@"key"];

}

@end