四、CAKeyframeAnimation (针动画)

CAKeyframeAnimation (针动画)

怎么理解这个(针动画)呢，举个例子给大家：

一个view,我们想它从点A移动到点B，再移动到点C,整一个动画就是针动画

它是根据你指定的一系路径去执行动画的，也就是一针一针的执行动画，要实现这些针动画效果，CATransition,CABaseAnimation是实现不了的。

下面给个代码小例子去体会下，大家可直接copy运行下:

//
//  ViewController.m
//  KeyFrameAnimation
//
//  Created by vincent_guo on 13-9-6.
//  Copyright (c) 2013年 vincent_guo. All rights reserved.
//

#import "ViewController.h"
#import <QuartzCore/QuartzCore.h>

@interface ViewController (){
    UIImageView *_imageView;
}

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
	// Do any additional setup after loading the view, typically from a nib.
    _imageView = [[UIImageView alloc] init];
    _imageView.bounds = CGRectMake(0, 0, 80, 80);
    _imageView.center = CGPointMake(160, 50);
    _imageView.image = [UIImage imageNamed:@"clock"];
    [self.view addSubview:_imageView];
    [_imageView release];
}

-(void)click:(id)sender{
    [self keyPathAnim];
}

#pragma mark 图片往下掉，再往上移动 看上去有反弹的效果
-(void)keyPathAnim{
    
    //position 代表位置属性，如中心点(x,y)的值
    CAKeyframeAnimation *positionAnimation = [CAKeyframeAnimation animationWithKeyPath:@"position"];
    positionAnimation.duration = 0.5;
    //定义个position(位置变换的路径)
    CGMutablePathRef path = CGPathCreateMutable();
    CGPathMoveToPoint(path, NULL, 160, 50);
    CGPathAddLineToPoint(path, NULL, 160, 100);
    CGPathAddLineToPoint(path, NULL, 160, 150);
    CGPathAddLineToPoint(path, NULL, 160, 200);
    CGPathAddLineToPoint(path, NULL, 160, 250);
    CGPathAddLineToPoint(path, NULL, 160, 235);//为什么移动的y值又小了，是因为想让它实现反弹的效果
    CGPathAddLineToPoint(path, NULL, 160, 250);
    positionAnimation.path = path;
    CGPathRelease(path);
    [_imageView.layer addAnimation:positionAnimation forKey:@"keyframeanimation"];//开始动画
    _imageView.center = CGPointMake(160, 250);//如果不写上这句，那么动画结束后,view返回到原来的位置
}

@end