iOS点赞动画 iOS实现点赞动画特效

时间:2021-01-29 mayifan_blog 人气:0

动画的基本使用

动画的实现基本上是基于对View控件和View的layer属性进行操作，对视图进行移动，尺寸变换，透明度变换，旋转等一系列操作。

关键帧动画：

动画的实现可以分为两个部分，一部分是规定动画的变化内容，比如view需要把scale从0变化到1，这个数字是相对值，即从尺寸为0变化到正常尺寸。另一个部分是规定动画的渐变时间。这样就实现了view在规定时间完成指定变化了，这个变化的过程也可以通过参数设置为非均匀变化的。上面的示例是关键帧动画的实现，实现的方式是把动画划分为几个部分，“第一帧”做一件事，“第二帧”再做另外一件事，这就使得变化连续且可控。Duration参数确定了时间，delay确定了延时多久执行，options确定了关键帧动画布局子控件。completion的参数是一个block，其中的内容是在内容执行结束后才调用。这里做了3帧，前两帧做了尺寸变为3倍然后恢复，后一帧使得其隐藏。结束后会调用block使其移除。

[UIView animateKeyframesWithDuration:self.animationDurtion * 4 delay:0.0 options:UIViewKeyframeAnimationOptionLayoutSubviews animations:^{
   /*参数1:关键帧开始时间
    参数2:关键帧占用时间比例
    参数3:到达该关键帧时的属性值 */
   [UIView addKeyframeWithRelativeStartTime:0.0 relativeDuration:0.5 * self.animationDurtion animations:^{
    giveLikeView.transform = CGAffineTransformMakeScale(3, 3);;
   }];
   [UIView addKeyframeWithRelativeStartTime:0.5 * self.animationDurtion relativeDuration:0.5 * self.animationDurtion animations:^{
    giveLikeView.transform = CGAffineTransformIdentity;
   }];
   [UIView addKeyframeWithRelativeStartTime:self.animationDurtion relativeDuration:self.animationDurtion * 3 animations:^{
    giveLikeView.alpha = 0;
   }];
  } completion:^(BOOL finished) {
   giveLikeView.hidden = YES;
   [giveLikeView removeFromSuperview];
  }];

CAShapeLayer和UIBezierPath：

当不满足于view的变化，还需要在view的表面绘制一些图案，就要对layer进行操作，layer可以理解为是view的表面，每个view都有layer参数。UIBezierPath是贝塞尔曲线，它用于设置绘图的路径，没有了它，layer的绘制也是无效的，因为没有边界呀。
如下代码绘制了一个圆形的曲线，设置了它的中心，半径，起始终止角这些属性。

UIBezierPath *bezierPath = [UIBezierPath bezierPathWithArcCenter:CGPointMake(giveLikeView.bounds.size.width/2, giveLikeView.bounds.size.height/2) radius:giveLikeView.bounds.size.width startAngle:-1.57 endAngle:-1.57+3.14*2 clockwise:YES];
 circleLayer.path = bezierPath.CGPath;
 [self.layer addSublayer:circleLayer];

在最后我们可以看到：circleLayer.path = bezierPath.CGPath; [self.layer addSublayer:circleLayer];
它的作用是设置layer的路径，并把layer添加到view的表面。下面来看看layer的配置。
创建一个layer后设置它的frame和颜色以及边界，线宽这些属性。

CAShapeLayer *circleLayer = [[CAShapeLayer alloc] init];
circleLayer.frame = giveLikeView.frame;
circleLayer.fillColor = [UIColor clearColor].CGColor;
circleLayer.strokeColor = [UIColor redColor].CGColor;
circleLayer.lineWidth = 1;

几处联系：把贝塞尔曲线和layer联系起来，把layer和view的layer联系起来。

为layer加动画（动画组）：

先创建动画组CAAnimationGroup，它可以容纳若干动画，然后创建若干CABasicAnimation基础动画。分别设置属性，动画组需要涉及的属性有时间功能，kCAMediaTimingFunctionEaseIn表示逐渐加快，另外还有设置持续时间，设置kCAFillModeForwards表示动画在结束后会保持，removedOnCompletion = NO表示最后不移除。在基础动画的设置中，一般设置在动画组中的起始时间和持续时间，还有参数的变化。最后的 group.animations = @[scaleAnimtion,widthStartAnimtion,widthEndAnimtion];[circleLayer addAnimation:group forKey:nil];
两句表示在动画组中添加动画然后为layer添加动画组，这样layer就有动画特效了。

//动画
CAAnimationGroup *group = [CAAnimationGroup animation];
 group.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn];
 NSTimeInterval groupInterval = self.animationDurtion * 0.8;
 group.duration = groupInterval;
 group.fillMode = kCAFillModeForwards;
 group.removedOnCompletion = NO;
 
CABasicAnimation * scaleAnimtion = [CABasicAnimation animationWithKeyPath:@"transform.scale"];
 scaleAnimtion.beginTime = 0;
 scaleAnimtion.duration = groupInterval * 0.8;
 scaleAnimtion.fromValue = @(0);
 scaleAnimtion.toValue = @(1);
 
CABasicAnimation * widthStartAnimtion = [CABasicAnimation animationWithKeyPath:@"lineWidth"];
 widthStartAnimtion.beginTime = 0;
 widthStartAnimtion.duration = groupInterval * 0.8;
 widthStartAnimtion.fromValue = @(1);
 widthStartAnimtion.toValue = @(2);
 
CABasicAnimation * widthEndAnimtion = [CABasicAnimation animationWithKeyPath:@"lineWidth"];
 widthEndAnimtion.beginTime = groupInterval * 0.8;
 widthEndAnimtion.duration = groupInterval * 0.2;
 widthEndAnimtion.fromValue = @(2);
 widthEndAnimtion.toValue = @(0);
 
 group.animations = @[scaleAnimtion,widthStartAnimtion,widthEndAnimtion];
 [circleLayer addAnimation:group forKey:nil];

点赞动画的实现原理

下面来介绍demo的实现原理。

controller的尺寸设置为全屏，在其上方也覆盖一个全屏的view，再在view上添加点击事件（手势）。

- (void)addGesture
{
 UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(creatOneHeart:)];
 [self addGestureRecognizer:tap]; 
}

下面看看点击后调用的方法：

这里每次点击都会获取点击的位置然后去初始化一个爱心，这是异步任务，放在主队列中执行。

- (void)creatOneHeart:(UITapGestureRecognizer *)sender
{
 CGPoint point = [sender locationInView:self];
 dispatch_async(dispatch_get_main_queue(),^{
  [self initOneNewHeart:point];
 });
}

这段代码创建了视图对象，这里自然用到了事先创建好的心形图片。这里把创建的imageview存到队列，显示到view上，最后调用likeAction:方法执行动画。

- (UIImageView *)createGiveLikeView
{
 UIImageView *giveLikeView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 40, 40)];
 giveLikeView.backgroundColor = [UIColor clearColor];
 UIImage *image = [UIImage imageNamed:@"icon_home_like_after"];
 giveLikeView.userInteractionEnabled = YES;
 giveLikeView.tag = GiveType;
 giveLikeView.image = image;
 giveLikeView.hidden = NO;
 _giveLikeView = giveLikeView;
 return _giveLikeView;
}
- (void)initOneNewHeart:(CGPoint)point
{
 UIImageView *giveLikeView = [self createGiveLikeView];
 giveLikeView.center = point;
 [self.array addObject:giveLikeView];
 [self addSubview:giveLikeView];
 [self likeAction:giveLikeView];
}

我们看看giveLikeAction：这个方法，它包括执行心形的变化动画和绘制六个辐射的三角形动画，还有辐散的圆的动画。

- (void)likeAction:(UIImageView *)giveLikeView
{
 [self giveLikeAction:giveLikeView];
}
- (void)giveLikeAction:(UIImageView *)giveLikeView
{
 [self animtionChangeLikeType:giveLikeView];
 [self createTrigonsAnimtion:giveLikeView];
 [self createCircleAnimation:giveLikeView];
}

接下来直接看看辐散的三角形的动画（爱心的变化动画在上面已经涉及到了）：
这段代码跑了6个循环，做了6个三角形，它们分别有动画效果。
shape.transform = CATransform3DMakeRotation(3.14 / 3 * i, 0, 0, 1);实现了旋转。
[giveLikeView.layer addSublayer:shape];执行layer的添加。
因为在循环中，每个layer都有独立的动画，动画组实现的效果是三角形从小变大，最后变成一条直线并消失。
下面的两行代码用到了__bridge，它的作用是实现类型的转换，这里把CGPathRef类型“桥接”转化为了id类型，如果没有它，会报错。
pathAnimation.fromValue = (__bridge id)startPath.CGPath;
pathAnimation.toValue = (__bridge id)endPath.CGPath;

- (void)createTrigonsAnimtion:(UIImageView *)giveLikeView
{
 for(int i=0;i<6;i++) {
  //创建一个layer并设置位置和填充色
  CAShapeLayer *shape = [[CAShapeLayer alloc] init];
  shape.position = CGPointMake(giveLikeView.bounds.size.width/2, giveLikeView.bounds.size.height/2);
  shape.fillColor = [UIColor redColor].CGColor;
  //设置贝塞尔曲线，执行路径
  UIBezierPath *startPath = [[UIBezierPath alloc] init];
  [startPath moveToPoint:CGPointMake(-2, 30)];
  [startPath addLineToPoint:CGPointMake(2, 30)];
  [startPath addLineToPoint:CGPointMake(0, 0)];
  [startPath addLineToPoint:CGPointMake(-2, 30)];
  shape.path = startPath.CGPath;
  
  //旋转
  shape.transform = CATransform3DMakeRotation(3.14 / 3 * i, 0, 0, 1);
  [giveLikeView.layer addSublayer:shape];
  
  //动画组
  CAAnimationGroup *groupAnimation = [CAAnimationGroup animation];
  groupAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn];
  groupAnimation.duration = self.animationDurtion;
  groupAnimation.fillMode = kCAFillModeForwards;
  groupAnimation.removedOnCompletion = NO;
  
  //基础动画1
  CABasicAnimation *scaleAnimtion = [CABasicAnimation animationWithKeyPath:@"transform.scale"];
  //缩放时间占20%
  scaleAnimtion.duration = self.animationDurtion * 0.2;
  scaleAnimtion.fromValue = @(0);
  scaleAnimtion.toValue = @(1);

  //绘制三角形结束 一条直线
  UIBezierPath *endPath = [UIBezierPath bezierPath];
  [endPath moveToPoint:CGPointMake(-2, 30)];
  [endPath addLineToPoint:CGPointMake(2, 30)];
  [endPath addLineToPoint:CGPointMake(0, 30)];

  //基础动画2
  CABasicAnimation *pathAnimation = [CABasicAnimation animationWithKeyPath:@"path"];
  pathAnimation.beginTime = self.animationDurtion * 0.2;
  pathAnimation.duration = self.animationDurtion * 0.8;
  pathAnimation.fromValue = (__bridge id)startPath.CGPath;
  pathAnimation.toValue = (__bridge id)endPath.CGPath;

  groupAnimation.animations = @[scaleAnimtion,pathAnimation];
  [shape addAnimation:groupAnimation forKey:nil];
 }
}

demo实现的动画效果

demo的GitHub链接

最后附上demo链接：MYFGiveLikeAnimationDemo

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