ViewController.m

在self.view上创建一个透明的View

  UIView *mainView=[[UIView alloc]initWithFrame:CGRectMake(-self.view.bounds.size.width*0.25,0,self.view.bounds.size.width,self.view.bounds.size.height)];
    
    mainView.backgroundColor = [UIColor lightGrayColor];
    
    [self.view addSubview:mainView];

添加tabbarController的view

- (void)addTabbarController
{
    _barVC = [[TabbarController alloc]init];

    [self addChildViewController:_barVC];
    
    [self.view addSubview:_barVC.view];
    
    _barVC.view.frame = self.view.bounds;
}

添加手势

-(void)addRecognizer{
    //    添加拖拽
    UIPanGestureRecognizer *pan=[[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(didPanEvent:)];
    
    [self.view addGestureRecognizer:pan];
}

实现拖拽

-(void)didPanEvent:(UIPanGestureRecognizer *)recognizer{
    
    // 1. 获取手指拖拽的时候, 平移的值
    CGPoint translation = [recognizer translationInView:_barVC.view];
    
    // 2. 让当前控件做响应的平移
    _barVC.view.transform = CGAffineTransformTranslate(_barVC.view.transform, translation.x, 0);
    
    [self.view.subviews objectAtIndex:1].ttx=[self.view.subviews objectAtIndex:2].ttx/3;
    
    // 3. 每次平移手势识别完毕后, 让平移的值不要累加
    [recognizer setTranslation:CGPointZero inView:_barVC.view];
    
    //获取最右边范围
    CGAffineTransform  rightScopeTransform=CGAffineTransformTranslate(self.view.transform,[UIScreen mainScreen].bounds.size.width*0.75, 0);
    
    //    当移动到右边极限时
    if (_barVC.view.transform.tx>rightScopeTransform.tx) {
        
        //        限制最右边的范围
        _barVC.view.transform=rightScopeTransform;
        //        限制透明view最右边的范围
        [self.view.subviews objectAtIndex:1].ttx=[self.view.subviews objectAtIndex:2].ttx/3;
        
        //        当移动到左边极限时
    }else if (_barVC.view.transform.tx<0.0){
        
        //        限制最左边的范围
        _barVC.view.transform=CGAffineTransformTranslate(self.view.transform,0, 0);
        //    限制透明view最左边的范围
        [self.view.subviews objectAtIndex:1].ttx=[self.view.subviews objectAtIndex:2].ttx/3;
        
    }
    //    当托拽手势结束时执行
    if (recognizer.state == UIGestureRecognizerStateEnded)
    {
        [UIView animateWithDuration:0.2 animations:^{
            
            if (_barVC.view.x >[UIScreen mainScreen].bounds.size.width*0.5) {
                
                _barVC.view.transform=rightScopeTransform;
                
                [self.view.subviews objectAtIndex:1].ttx=_barVC.view.ttx/3;
                
            }else{
                
                _barVC.view.transform = CGAffineTransformIdentity;
                
                [self.view.subviews objectAtIndex:1].ttx=_barVC.view.ttx/3;
            }
        }];
    }
}