用杯赛尔曲线（做动画和绘图）

- (void)clickButton:(id)sender
{
　　UIBezierPath *path = [UIBezierPath bezierPath];
　　[path moveToPoint:btn.center];
　　[path addCurveToPoint:btn.center
　　controlPoint1:CGPointMake(20, 300)
　　controlPoint2:CGPointMake(300, 460)];
 
 
　　//位置
　　CAKeyframeAnimation *animation = [CAKeyframeAnimation animationWithKeyPath:@"position"];
　　animation.path = path.CGPath;
 
　　//缩放
　　CABasicAnimation *scaleAnim = [CABasicAnimation animationWithKeyPath:@"transform"];
　　scaleAnim.fromValue = [NSValue valueWithCATransform3D:CATransform3DIdentity];
　　scaleAnim.toValue = [NSValue valueWithCATransform3D:CATransform3DMakeScale(0.1, 0.1, 1.0)];
 
　　//透明度
　　CABasicAnimation *alphaAnimation = [CABasicAnimation animationWithKeyPath:@"opacity"];//不是用alpha
　　alphaAnimation.fromValue=[NSNumber numberWithFloat:1.0];
　　alphaAnimation.toValue=[NSNumber numberWithFloat:0.1];
 
　　//动画组
　　CAAnimationGroup *groups = [CAAnimationGroup animation];
　　groups.animations = [NSArray arrayWithObjects:animation, alphaAnimation, scaleAnim,nil];
　　groups.duration = 5.0f;
　　groups.removedOnCompletion = NO;
　　groups.fillMode = kCAFillModeForwards;
　　groups.delegate = self;
　　[groups setValue:@"groupsAnimation" forKey:@"animationName"];
　　[btn.layer addAnimation:groups forKey:@"poaasgdsition scale"];
}
 
//这个方法竟然是来自NSObject
- (void)animationDidStop:(CAAnimation *)anim finished:(BOOL)flag
{
    NSLog(@"Finished");
}

- (void)drawThirdBezierPath {

  UIBezierPath *path = [UIBezierPath bezierPath];
  
  // 设置起始端点
  [path moveToPoint:CGPointMake(20, 150)];
  
  [path addCurveToPoint:CGPointMake(300, 150)
          controlPoint1:CGPointMake(160, 0)
          controlPoint2:CGPointMake(160, 250)];
  
  path.lineCapStyle = kCGLineCapRound;
  path.lineJoinStyle = kCGLineJoinRound;
  path.lineWidth = 5.0;
  
  UIColor *strokeColor = [UIColor redColor];
  [strokeColor set];
  
  [path stroke];
}

参考IOS7 Programming Cookbook ch20

#import <UIKit/UIKit.h>
@interface TestView : UIView
@end

@implementation TestView

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
　　　　[self setBackgroundColor:[UIColor clearColor]];
    }
    return self;
}

-(void)setImage2:(UImage *img)
{
   [self setneesDisplay];
}

// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
　　//draw string1
　　NSString *str = @"abc";
　　UIFont *font = [UIFont fontWithName:@"HelveticaNeue-Bold" size:10.0f];
　　[str drawAtPoint:CGPointMake(0,0)
  　　withAttributes:@{
 　　 NSFontAttributeName:font,
 　　 NSForegroundColorAttributeName:[UIColor redColor]
  　　}];

　　//draw string2
　　NSString *str2 = @"abc2";
　　UIFont *font2 = [UIFont fontWithName:@"HelveticaNeue-Bold" size:12.0f];
　　[str2 drawAtPoint:CGPointMake(40,0)
 　　 withAttributes:@{
  　　NSFontAttributeName:font2,
  　　NSForegroundColorAttributeName:[UIColor greenColor]
  　　}];

　　//draw image1
　　UIImage *img = [UIImage imageNamed:@"voice.png"];
　　[img drawAtPoint:CGPointMake(0, 0)];

　　//draw image2
　　[img drawInRect:CGRectMake(80, 80, 20, 10)];

　　//draw Line
　　[[UIColor brownColor] set];

　　CGContextRef currentContext = UIGraphicsGetCurrentContext();
　　CGContextSetLineWidth(currentContext, 4.0f);
　　CGContextSetLineJoin(currentContext, kCGLineJoinRound);//接缝处
　　CGContextMoveToPoint(currentContext, 20, 20);
　　CGContextAddLineToPoint(currentContext, 50, 80);
　　CGContextAddLineToPoint(currentContext, 100, 10);
　　CGContextStrokePath(currentContext);
}
@end