用path动画绘制水波纹

//
//  ViewController.m
//  PathAnimation
//
//  Created by YouXianMing on 15/7/3.
//  Copyright (c) 2015年 YouXianMing. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()

@property (nonatomic, strong)  CAShapeLayer   *animationLayer;
@property (nonatomic, strong)  NSTimer        *timer;

@property (nonatomic)          CGPathRef       oldPath;
@property (nonatomic)          CGPathRef       path;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    self.animationLayer               = [CAShapeLayer layer];
    self.animationLayer.borderWidth   = 0.5f;
    self.animationLayer.frame         = CGRectMake(0, 0, 200, 200);
    self.animationLayer.position      = self.view.center;
    self.animationLayer.path          = [self createPath].CGPath;
    self.animationLayer.fillColor     = [UIColor redColor].CGColor;
    [self.view.layer addSublayer:self.animationLayer];
    _timer = [NSTimer scheduledTimerWithTimeInterval:0.5f target:self selector:@selector(event) userInfo:nil repeats:YES];
}

- (void)event {
    
    _oldPath = self.animationLayer.path;
    _path    = [self createPath].CGPath;
    
    CABasicAnimation *basicAnimation   = [CABasicAnimation animationWithKeyPath:@"path"];
    basicAnimation.duration            = 0.5;
    basicAnimation.fromValue           = (__bridge id)(_oldPath);
    basicAnimation.toValue             = (__bridge id)_path;
    self.animationLayer.path           = _path;
    
    [self.animationLayer addAnimation:basicAnimation forKey:@"animateCirclePath"];
}

- (UIBezierPath *)createPath {
    
    static int count = 0;
    
    CGFloat controlPoint1_X = 0;
    CGFloat controlPoint1_Y = 0;
    CGFloat controlPoint2_X = 0;
    CGFloat controlPoint2_Y = 0;
    
    if (count ++ % 2 == 0) {
        
        controlPoint1_X = [self randomNum_70_79];
        controlPoint1_Y = [self randomNum_70_79];
        
        controlPoint2_X = [self randomNum_120_129];
        controlPoint2_Y = [self randomNum_120_129];
        
    } else {
    
        controlPoint1_X = [self randomNum_70_79];
        controlPoint1_Y = [self randomNum_120_129];
        
        controlPoint2_X = [self randomNum_120_129];
        controlPoint2_Y = [self randomNum_70_79];
        
    }
    
    // 获取贝塞尔曲线
    UIBezierPath* bezierPath = [UIBezierPath bezierPath];
    
    // A
    [bezierPath moveToPoint:CGPointMake(0, 100)];
    
    // B (Curve)
    [bezierPath addCurveToPoint:CGPointMake(200, 100)
                  controlPoint1:CGPointMake(controlPoint1_X, controlPoint1_Y)
                  controlPoint2:CGPointMake(controlPoint2_X, controlPoint2_Y)];
    
    // C
    [bezierPath addLineToPoint:CGPointMake(200, 200)];
    
    // D
    [bezierPath addLineToPoint:CGPointMake(0, 200)];
    
    // 闭合曲线
    [bezierPath closePath];
    
    return bezierPath;
}

/**
 *  随机数 70 - 79
 *
 *  @return 随机数
 */
- (CGFloat)randomNum_70_79 {

    return (CGFloat)(arc4random() % 10 + 70);
}

/**
 *  随机数 120 - 129
 *
 *  @return 随机数
 */
- (CGFloat)randomNum_120_129 {

    return (CGFloat)(arc4random() % 10 + 120);
}

@end