CAKeyframeAnimation

CAKeyframeAnimation跟CABasicAnimation的区别是：CABasicAnimation只能从一个Value变到另一个Value，而CAKeyframeAnimation会将这些数值保存在数组中或者以路径(path)形式保存.

另附代码如下:

- (instancetype)initWithFrame:(CGRect)frame withSuperView:(UIView *)superView{    if (self = [super initWithFrame:frame]) {                self.superView = superView;        self.borderColor = [UIColor whiteColor];        self.fillColor = [UIColor colorWithRed:(arc4random_uniform(255))/255.0 green:(arc4random_uniform(255))/255.0 blue:(arc4random_uniform(255))/255.0 alpha:1];        self.backgroundColor = [UIColor clearColor];        self.layer.anchorPoint = CGPointMake(0.5, 1);    }    return self;}- (void)addAnimationView{    // 初始化    self.transform = CGAffineTransformMakeScale(0, 0);    self.alpha = 0;        [UIView animateWithDuration:0.5 delay:0.0 usingSPRingWithDamping:0.6 initialSpringVelocity:0.8 options:UIViewAnimationOptionCurveEaSEOut animations:^{        self.transform = CGAffineTransformIdentity;        self.alpha = 0.9;    } completion:^(BOOL finished) {            }];    // 随机数    NSInteger i = arc4random_uniform(2);    NSInteger rotationDirection = 1 - (2*i);        // 绘制路径    UIBezierPath *heartTravelPath = [UIBezierPath bezierPath];    [heartTravelPath moveToPoint:self.center];        CGPoint endPoint = CGPointMake(self.centerX + (rotationDirection) * arc4random_uniform(2*self.width), self.superView.height/6.0 + arc4random_uniform(self.superView.height/4.0));    CGFloat x = (self.width/2.0 + arc4random_uniform(2*self.width)) * rotationDirection;    CGFloat y = MAX(endPoint.y ,MAX(arc4random_uniform(8*self.width), self.width));    CGPoint controlPoint1 = CGPointMake(self.centerX + x, self.superView.height - y);    CGPoint controlPoint2 = CGPointMake(self.centerX - 2*x, y);        [heartTravelPath addCurveToPoint:endPoint controlPoint1:controlPoint1 controlPoint2:controlPoint2];        CAKeyframeAnimation *keyFrameAnimation = [CAKeyframeAnimation animationWithKeyPath:@"position"];    keyFrameAnimation.path = heartTravelPath.CGPath;    keyFrameAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];    keyFrameAnimation.duration = liveAnimationDuration + endPoint.y/self.superView.height;    [self.layer addAnimation:keyFrameAnimation forKey:@"positionOnPath"];        [UIView animateWithDuration:liveAnimationDuration animations:^{        self.alpha = 0.0;    } completion:^(BOOL finished) {        [self removeFromSuperview];    }];}- (void)drawRect:(CGRect)rect{        [self.fillColor setFill];    [self.borderColor setStroke];        CGFloat drawingPadding = 2.0;    CGFloat curveRadius = floor((CGRectGetWidth(rect) - 2*drawingPadding) / 4.0);        UIBezierPath *heartPath = [UIBezierPath bezierPath];        CGPoint tipLocation = CGPointMake(floor(CGRectGetWidth(rect) / 2.0), CGRectGetHeight(rect) - drawingPadding);    [heartPath moveToPoint:tipLocation];        CGPoint topLeftCurveStart = CGPointMake(drawingPadding, floor(CGRectGetHeight(rect) / 3));        [heartPath addQuadCurveToPoint:topLeftCurveStart controlPoint:CGPointMake(topLeftCurveStart.x, topLeftCurveStart.y + curveRadius)];        [heartPath addArcWithCenter:CGPointMake(topLeftCurveStart.x + curveRadius, topLeftCurveStart.y) radius:curveRadius startAngle:M_PI endAngle:0 clockwise:YES];        CGPoint topRightCurveStart = CGPointMake(topLeftCurveStart.x + 2*curveRadius, topLeftCurveStart.y);    [heartPath addArcWithCenter:CGPointMake(topRightCurveStart.x + curveRadius, topRightCurveStart.y) radius:curveRadius startAngle:M_PI endAngle:0 clockwise:YES];        CGPoint topRightCurveEnd = CGPointMake(topLeftCurveStart.x + 4*curveRadius, topRightCurveStart.y);    [heartPath addQuadCurveToPoint:tipLocation controlPoint:CGPointMake(topRightCurveEnd.x, topRightCurveEnd.y + curveRadius)];        [heartPath fill];        heartPath.lineWidth = 1;    heartPath.lineCapStyle = kCGLineCapRound;    heartPath.lineJoinStyle = kCGLineCapRound;    [heartPath stroke];}
注:
values:动画移动的点
path：动画移动路径。path只对CALayer的anchorPoint和position起作用。path比values优先级高,所以如果path有值，那么values将被忽略.
keyTimes：为对应的关键帧设置对应的时间点(取值范围为0到1.0),keyTimes中的每一个时间值都对应values中的每一帧.默认各个关键帧的时间是平分的.