第三段：从C点返回原点
三、实现代码
1、第一段运动：
确定起始点、圆心、半径，让蓝色小球绕大圆
//动画容器的宽度
CGFloat width = _ballContainer.bounds.size.width;
//小圆半径
CGFloat r = (_ball1.bounds.size.width)*ballScale/2.0f;
//大圆半径
CGFloat R = (width/2 + r)/2.0;
UIBezierPath *path1 = [UIBezierPath bezierPath];
//设置起始位置
[path1 moveToPoint:_ball1.center];
//画大圆（第一段的运动轨迹）
[path1 addArcWithCenter:CGPointMake(R + r, width/2) radius:R startAngle:M_PI endAngle:M_PI*2 clockwise:NO];
2、第二段运动
以灰色小球中心为圆心，以其直径为半径绕小圆，并拼接两段曲线
//画小圆
UIBezierPath *path1_1 = [UIBezierPath bezierPath];
//圆心为灰色小球的中心 半径为灰色小球的半径
[path1_1 addArcWithCenter:CGPointMake(width/2, width/2) radius:r*2 startAngle:M_PI*2 endAngle:M_PI clockwise:NO];
[path1 appendPath:path1_1];
3、第三段运动
//回到原处
[path1 addLineToPoint:_ball1.center];
4、位移动画
利用关键帧动画实现小球沿设置好的贝塞尔曲线移动
//执行动画
CAKeyframeAnimation *animation1 = [CAKeyframeAnimation animationWithKeyPath:@"position"];
animation1.path = path1.CGPath;
animation1.removedOnCompletion = YES;
animation1.duration = [self animationDuration];
animation1.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
[_ball1.layer addAnimation:animation1 forKey:@"animation1"];
5、缩放动画
在每次位移动画开始时执行缩放动画
-(void)animationDidStart:(CAAnimation *)anim{
CGFloat delay = 0.3f;
CGFloat duration = [self animationDuration]/2 - delay;
[UIView animateWithDuration:duration delay:delay options:UIViewAnimationOptionCurveEaseOut| UIViewAnimationOptionBeginFromCurrentState animations:^{
_ball1.transform = CGAffineTransformMakeScale(ballScale, ballScale);
_ball2.transform = CGAffineTransformMakeScale(ballScale, ballScale);
_ball3.transform = CGAffineTransformMakeScale(ballScale, ballScale);
} completion:^(BOOL finished) {
[UIView animateWithDuration:duration delay:delay options:UIViewAnimationOptionCurveEaseInOut| UIViewAnimationOptionBeginFromCurrentState animations:^{
_ball1.transform = CGAffineTransformIdentity;
_ball2.transform = CGAffineTransformIdentity;
_ball3.transform = CGAffineTransformIdentity;
} completion:nil];
}];
}
6、动画循环
在每次动画结束时从新执行动画
