RBBAnimation是CAKeyframeAnimation的一个子类，它可以让你使用block来声明动画，而不需要写出所有单独的key-frames。


这样在指定动画效果的时候就灵活很多，而且你也可以保持代码的简洁。


RBBCustomAnimation
使用RBBCustomAnimation，通过传递一个RMBBAnimationBlock来创建一个随机的动画。

RBBCustomAnimation *rainbow = [RBBCustomAnimation animationWithKeyPath:@"backgroundColor"];



rainbow.animationBlock = ^(CGFloat elapsed, CGFloat duration) {

    UIColor *color = [UIColor colorWithHue:elapsed / duration

                                saturation:1

                                brightness:1

                                     alpha:1];



    return (id)color.CGColor;

};

RBBSpringAnimation
RBBSpringAnimation是CASpringAnimation很好用的一个替代品。指定弹跳物体的质量，阻尼，刚度以及初始速度之后你可以可以看物体弹跳的效果了。

RBBSpringAnimation *spring = [RBBSpringAnimation animationWithKeyPath:@"position.y"];



spring.fromValue = @(-100.0f);

spring.toValue = @(100.0f);

spring.velocity = 0;

spring.mass = 1;

spring.damping = 10;

spring.stiffness = 100;



spring.additive = YES;

spring.duration = [spring durationForEpsilon:0.01];

RBBTweenAnimation

RBBTweenAnimation允许你设置动画的值，和CABasicAnimation类似，但是比它的灵活性更大。

它支持使用RBBCubicBezier帮助功能的CAMediaTimingFunction中获得的三次贝塞尔曲线的插值：

RBBTweenAnimation *easeInOutBack = [RBBTweenAnimation animationWithKeyPath:@"position.y"];



easeInOutBack.fromValue = @(-100.0f);

easeInOutBack.toValue = @(100.0f);

easeInOutBack.easing = RBBCubicBezier(0.68, -0.55, 0.265, 1.55);



easeInOutBack.additive = YES;

easeInOutBack.duration = 0.6;

然而，RBBTweenAnimation同时还支持更复杂的一些缓动功能，比如说RBBEasingFunctionEaseOutBounce：

RBBTweenAnimation *bounce = [RBBTweenAnimation animationWithKeyPath:@"position.y"];

bounce.fromValue = @(-100);

bounce.toValue = @(100);

bounce.easing = RBBEasingFunctionEaseOutBounce;



bounce.additive = YES;

bounce.duration = 0.8;

你还可以指定你自己的缓动功能：

RBBTweenAnimation *sinus = [RBBTweenAnimation animationWithKeyPath:@"position.y"];

sinus.fromValue = @(0);

sinus.toValue = @(100);



sinus.easing = ^CGFloat (CGFloat fraction) {

    return sin((fraction) * 2 * M_PI);

};



sinus.additive = YES;

sinus.duration = 2;