Cell选中 图片放大

今天给 UICollectionViewCell 添加一个点击放大图片的效果 类似button的选中高亮效果，
放大方式：使用添加动画放大
(1)添加手势的，手势只能创建 单击 移动分开等，还会禁止掉 didSelectItemAtIndexPath
(2)我采用 touch相关方法 来处理---为了不用修改didSelectItemAtIndexPath 只在cell中添加相关代码即可

采用 2 的方式
实现功能是

1.点击cell后 --添加动画

2.手势 end/move出cell 取消动画  collectionView滑动后 也取消动画

具体代码：
手势监听

下面调用super，是为了不影响didSelectItemAtIndexPath 等方法的调用
(有部分没有调用super的时候，didSelectItemAtIndexPath有时候不能正常响应)

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    [self addAnimationTransformScale];
    [super touchesBegan:touches withEvent:event];
}

-(void)touchesEnded:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    [self removeAnimation];
    [super touchesEnded:touches withEvent:event];
}
- (void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    UITouch *touch=[touches anyObject];
    //取得当前位置
    CGPoint current=[touch locationInView:self];
    if (NO == [self pointInside:current withEvent:event]) {
        [self removeAnimation];
    }
    [super touchesMoved:touches withEvent:event];
}
// scrollview滑动或者打电话等 中断
- (void)touchesCancelled:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    [self removeAnimation];
    [super touchesCancelled:touches withEvent:event];
}

添加和删除动画

- (void)removeAnimation {
    [self.imageView.layer removeAllAnimations];
}
- (void)addAnimationTransformScale {
    CABasicAnimation*pulse = [CABasicAnimation animationWithKeyPath:@"transform.scale"];
    pulse.timingFunction= [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
    pulse.duration = 0.08;
    pulse.fillMode = kCAFillModeForwards; //保留动画最后的状态
    pulse.fromValue= [NSNumber numberWithFloat:1];
    pulse.toValue= [NSNumber numberWithFloat:1.3];
    pulse.removedOnCompletion = NO;
    [self.imageView.layer addAnimation:pulse forKey:nil];
}