核心动画——弹簧动画一主要介绍弹簧动画的一些属性，下面介绍一下弹簧动画的另一种效果。
首先在Main.storyboard文件里面创建一个UIButton，ViewController继承于ViewController。将UIButton设置为一个属性，选中UIButton右击不放手拖到ViewController.m文件的@interface 里面并给它起名。同时，给它一个触发事件，将它拖到@implementation里面。具体操作看代码:
#import "ViewController.h"
@interface ViewController ()
@property (weak, nonatomic) IBOutlet UIButton *annimationButton;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
}
- (IBAction)action:(id)sender {
UIButton *button = sender;
button.selected = !button.selected;
button.backgroundColor = button.selected != YES?[UIColor colorWithRed:1.000 green:0.435 blue:0.812 alpha:1.000]:[UIColor colorWithRed:0.400 green:0.800 blue:1.000 alpha:1.000];
[self jump];
}
- (void)jump{
CASpringAnimation *animation = [CASpringAnimation animationWithKeyPath:@"bounds"];
animation.toValue = [NSValue valueWithCGRect:CGRectMake(0, 0, self.annimationButton.frame.size.width*1.5, self.annimationButton.frame.size.height*1.5)];
animation.mass = 2;
animation.stiffness = 100;
animation.damping = 3;
animation.initialVelocity = 30;
animation.duration = animation.settlingDuration;
[self.annimationButton.layer addAnimation:animation forKey:@"jump"];
}
- (void)move:(CGPoint)toPoint{
CABasicAnimation *basicAnimation = [CABasicAnimation animationWithKeyPath:@"position"];
basicAnimation.toValue = [NSValue valueWithCGPoint:toPoint];
basicAnimation.duration = 3;
basicAnimation.removedOnCompletion = NO;
basicAnimation.fillMode = kCAFillModeBoth;
[self.annimationButton.layer addAnimation:basicAnimation forKey:@"move"];
}
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
[self move:[[touches anyObject] locationInView:self.view]];
NSLog(@"button改变位置之前的中心点x:%f y:%f",self.annimationButton.center.x,self.annimationButton.center.y);
NSLog(@"button上面Layer的中心点x:%f y:%f",self.annimationButton.layer.position.x,self.annimationButton.layer.position.y);
//CAAnimation 只是改变图层的动画效果，并没有真实的改变视图、图层的属性值
}
@end
它的效果:
