用Easing函数实现碰撞效果

工程中需要的源码请从这里下载：

https://github.com/YouXianMing/EasingAnimation

源码：

//
//  ViewController.m
//  EasingView
//
//  Created by YouXianMing on 15/1/17.
//  Copyright (c) 2015年 YouXianMing. All rights reserved.
//

#import "ViewController.h"
#import "YXEasing.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    // 显示的view
    UIView *showView            = [[UIView alloc] initWithFrame:CGRectMake(100, -100, 100, 100)];
    showView.backgroundColor    = [UIColor clearColor];
    showView.layer.borderColor  = [UIColor redColor].CGColor;
    showView.layer.borderWidth  = 4.f;
    showView.layer.cornerRadius = 50.f;
    [self.view addSubview:showView];

    // 关键帧动画
    CAKeyframeAnimation *animation = [CAKeyframeAnimation animationWithKeyPath:@"position"];

    // 设置值
    [animation setValues:[YXEasing calculateFrameFromPoint:showView.center
                                                   toPoint:CGPointMake(showView.center.x, showView.center.y + 565)
                                                      func:BounceEaseOut
                                                frameCount:100]];

    // 设置持续时间
    animation.duration  = 1.f;

    // 执行动画效果
    showView.center = CGPointMake(showView.center.x, showView.center.y + 565);
    [showView.layer addAnimation:animation forKey:nil];
}

@end