实践 -实现一款中间凸起的TabBar

@interface MCTabBar : UITabBar
@property (nonatomic, strong) UIButton *centerBtn; //中间按钮
@end

@implementation MCTabBar
- (instancetype)init{
    if (self = [super init]){
        [self initView];
    }
      return self;
}

- (void)initView{
      _centerBtn = [UIButton buttonWithType:UIButtonTypeCustom];
    //  设定button大小为适应图片
     UIImage *normalImage = [UIImage imageNamed:@"tabbar_add"];
    _centerBtn.frame = CGRectMake(0, 0, normalImage.size.width+10, normalImage.size.height+10);
    [_centerBtn setImage:normalImage forState:UIControlStateNormal];
    //去除选择时高亮
    _centerBtn.adjustsImageWhenHighlighted = NO;
    //根据图片调整button的位置(图片中心在tabbar的中间最上部，这个时候由于按钮是有一部分超出tabbar的，所以点击无效，要进行处理)
    _centerBtn.frame = CGRectMake(([UIScreen mainScreen].bounds.size.width - normalImage.size.width-10)/2.0, - normalImage.size.height/2.0-5, normalImage.size.width+10, normalImage.size.height+10);
    [self addSubview:_centerBtn];
}

//处理超出区域点击无效的问题
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event{
    UIView *view = [super hitTest:point withEvent:event];
    if (view == nil){
      //转换坐标
      CGPoint tempPoint = [self.centerBtn convertPoint:point fromView:self];
      //判断点击的点是否在按钮区域内
      if (CGRectContainsPoint(self.centerBtn.bounds, tempPoint)){
          //返回按钮
          return _centerBtn;
      }

    //******************    或者使用这个方法     ****************
    
      //判断如果这个新的点是在发布按钮身上，那么处理点击事件最合适的view就是发布按钮
      if ( [self.centerBtn pointInside:point withEvent:event]) {
            return self.centerBtn;
      }else{//如果点不在发布按钮身上，直接让系统处理就可以了
          return [super hitTest:point withEvent:event];
      }
    }
    return view;
}

- (CGPoint)convertPoint:(CGPoint)point toView:(nullable UIView *)view;
- (CGPoint)convertPoint:(CGPoint)point fromView:(nullable UIView *)view;

[fromView convertPoint:point toView:toView];
[toView convertPoint:point fromView:fromView];

 MedicalViewController *vc2=[[MedicalViewController alloc] init];
  vc2.title=@"医疗";
 vc2.tabBarItem.image=[[UIImage imageNamed:@""] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
 vc2.tabBarItem.selectedImage=[[UIImage imageNamed:@""] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];

    _mcTabbar = [[MCTabBar alloc] init];
    [_mcTabbar.centerBtn addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside];
    //选中时的颜色
    _mcTabbar.tintColor = [UIColor colorWithRed:27.0/255.0 green:118.0/255.0 blue:208/255.0 alpha:1];
    //透明设置为NO，显示白色，view的高度到tabbar顶部截止，YES的话到底部
    _mcTabbar.translucent = NO;
    //利用KVC 将自己的tabbar赋给系统tabBar
    [self setValue:_mcTabbar forKeyPath:@"tabBar"];

 - (void)buttonAction:(UIButton *)button{
      self.selectedIndex = 1;//关联中间按钮
      [self rotationAnimation];
  }

//tabbar选择时的代理
- (void)tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController *)viewController{
  if (tabBarController.selectedIndex == 1){//选中中间的按钮
      [self rotationAnimation];
  }else {
      [_mcTabbar.centerBtn.layer removeAllAnimations];
  }
}
//旋转动画
- (void)rotationAnimation{

    CABasicAnimation *rotationAnimation = [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];
    rotationAnimation.toValue = [NSNumber numberWithFloat:M_PI*2.0];
    rotationAnimation.duration = 3.0;
    rotationAnimation.repeatCount = HUGE;
    [_mcTabbar.centerBtn.layer addAnimation:rotationAnimation forKey:@"key"];
}