使用UIImageView加上CAAnimation实现
小萌图动画由三个部分组成：
1.改变大小动画
2.改变位置动画
3.改变透明度动画
下面是实现方式
新建一个UIImageView类
这里是在init方法里初始化的动画
- (instancetype)initWithImage:(UIImage*)image withStartPoint:(CGPoint)point withXlength:(NSInteger)xlengthwithYlength:(double)ylength byDuration:(NSInteger)durationTime{
if(self= [superinitWithImage:image]) {
//位置移动动画
CAKeyframeAnimation*keyAnima_group2=[CAKeyframeAnimationanimationWithKeyPath:@"position"];
//动画的速度变化 这里为线性 匀速的
keyAnima_group2.timingFunction=[CAMediaTimingFunctionfunctionWithName:kCAMediaTimingFunctionLinear];
keyAnima_group2.duration= durationTime; //动画时间
keyAnima_group2.removedOnCompletion=NO;//fillMode生效 必须设为NO
keyAnima_group2.fillMode=kCAFillModeRemoved;//动画开始前及结束后 动画都移除
//使用路径来设置位置动画
CGPathRefcurvedPath = [selfheartPath:pointwithXlength:xlengthwithYlength:ylength];
keyAnima_group2.path= curvedPath;
CGPathRelease(curvedPath);
//缩放动画：
CABasicAnimation*theAnimation=[CABasicAnimationanimationWithKeyPath:@"transform.scale"];
theAnimation.duration=durationTime;
theAnimation.fromValue= [NSNumbernumberWithFloat:0.7];
theAnimation.toValue= [NSNumbernumberWithFloat:1.2];
theAnimation.removedOnCompletion=NO;
theAnimation.fillMode=kCAFillModeRemoved;
//透明度动画
CABasicAnimation*opacityAnimation = [CABasicAnimationanimationWithKeyPath:@"opacity"];
opacityAnimation.fromValue= [NSNumbernumberWithFloat:1.0];
opacityAnimation.toValue= [NSNumbernumberWithFloat:0];
opacityAnimation.duration=durationTime;
opacityAnimation.removedOnCompletion=NO;
opacityAnimation.fillMode=kCAFillModeForwards;//动画结束保留结束状态 此处设该值是因为动画开始后APP切后台会造成动画不被移除 保留透明状态可解决
[self.layer addAnimation:opacityAnimationforKey:@"animateTransform.opacity"];//额外增加一次动画 防止动画结束的后会在imageView初始化的位置出现
//组合两个动画
CAAnimationGroup* g = [CAAnimationGroupanimation];
g.animations=@[keyAnima_group2,theAnimation,opacityAnimation];
g.duration= durationTime;
g.removedOnCompletion=NO;
g.fillMode=kCAFillModeRemoved;
g.beginTime=CACurrentMediaTime();
g.delegate=self;
[self.layeraddAnimation:gforKey:@"g"];
self.animationGroup= g;
}
return self;
}
然后是位移动画path生成部分
#pragma mark private mothed
- (CGPathRef)heartPath:(CGPoint)point withXlength:(NSInteger)xlengthwithYlength:(double)ylength
{
int y =8+(arc4random() %2);//y轴移动次数
int yHeight = point.y/8;//每次y轴移动高度
int direction =arc4random() %4;//用于x轴移动方向判断
CGMutablePathRefcurvedPath =CGPathCreateMutable();//使用UIBezierPath，路径数值不正常，超出父视图范围，有兴趣的可以试试
CGPathMoveToPoint(curvedPath,NULL, point.x, point.y);//起始位置
for(inti =0;i<y;i++){
if(point.y-yHeight-yHeight*i <=0) {//超过Y轴最大范围就停止
break;
}
xNSIntegerxWidth = (arc4random() % xlength);//每次x轴移动距离
if(direction%2==0) {//方向随机
xWidth = -xWidth;
}
CGPathAddLineToPoint(curvedPath,NULL,point.x+xWidth, point.y-yHeight-yHeight*i);
}
return curvedPath;
}
然后在animation delegate里移除layer层动画
- (void)animationDidStop:(CAAnimation*)anim finished:(BOOL)flag {
if(flag) {
[self.layer removeAllAnimations];
}
}
外面调用时
intimageNum = (arc4random() %7);
UIImage*image = [UIImageimageNamed:[NSStringstringWithFormat:@"小萌图-%d",imageNum]];//随机图片
heartImageView*animation = [[heartImageView alloc]initWithImage:image withStartPoint:CGPointMake(CGRectGetWidth(self.frame) /2,CGRectGetHeight(self.frame) - image.size.height/2) withXlength:10 withYlength:50 byDuration:3];
[self addSubview:animation];
}
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