iOS仿今日头条滑动导航

之前写了篇博客网易首页导航封装类、网易首页导航封装类优化,今天在前两个的基础上仿下今日头条。

1.网易首页导航封装类中主要解决了上面导航的ScrollView和下面的页面的ScrollView联动的问题,以及上面导航栏的偏移量。

2.网易首页导航封装类优化中主要解决iOS7以上滑动返回功能中UIScreenEdgePanGestureRecognizer与ScrollView的滑动的手势冲突问题。

今天仿今日头条滑动导航和网易首页导航封装类优化相似,这个也是解决手势冲突,UIPanGestureRecognizer与ScrollView的手势冲突。

一、ViewController的层次

用上面的图来介绍,左侧的个人页面ViewController上面通过addChildViewController添加了一个以MainViewController为RootViewController的

UINavigationController,通过addSubview将UINavigationController的View添加到个人页面ViewController的View上。

二、仿今日头条滑动导航主要有4个问题:

1.UIPanGestureRecognizer与ScrollView的手势冲突

为了达到拖动滑动的效果，需要给MainViewController添加一个UIPanGestureRecognizer,由于底部是ScrollView和TableView组成的，所以会使UIPanGestureRecognizer与底部的冲突,和网易首页导航封装类优化类似需要在

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer中根据gestureRecognizer返回YES来使ScrolView和UIPanGestureRecognizer都识别。

2.UIPanGestureRecognizer滑动结束的位置不正确

用UIPanGestureRecognizer滑动根据偏移量来改变UINavigationController的View的位置,在今日头条中滑动结束时UINavigationController的View要么在原位要么在右侧，不会停在中间,这个问题让我想起了之前做的果冻效果,手势有状态state,根据手势的状态来改变UINavigationController的View的位置,特别是在手势结束时。

3.由于1使ScrolView和UIPanGestureRecognizer都识别,导致返回时ScrolView也会滑动

让底部的ScrolView能滑动的时间应该是UINavigationController的View在初始位置frame的x为0，所以在它的frame的x>0时,底部的bottomScrollView scrollEnabled=NO。

4.页面拖到右边时点击右边页面可以滑到初始位置

首先时点击滑到初始页面则需要给UINavigationController的View添加轻点手势,添加后就会与tableView的手势冲突,所以有出现了一个新的bug,解决这个bug还比较好解决,因为bottomScrollView的ScrollView只有Pan、pich手势,tap手势没有，所以只要设置tap轻点手势的状态就能解决. 在UINavigationController的View的frame的x>0时，tap手势的enable＝NO，＝＝0时为Yes即可(上周未将轻点加上,这周算是补上了,下面具体实现代码我就不改了)。

三、 主要实现代码(导航的代码就不贴了,只贴主要的)

1.声明一个拖动手势

@property(nonatomic,strong) UIPanGestureRecognizer *panGestureRecognizer;

2.为MainViewController添加手势

 _panGestureRecognizer=[[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(panGesture:)];
    _panGestureRecognizer.delegate=self;
    [self.navigationController.view addGestureRecognizer:_panGestureRecognizer];

3.手势识别的方法

//平移
-(void)panGesture:(UIPanGestureRecognizer*)pan
{
    //在View中的位置
//    CGPoint point=[pan locationInView:self.navigationController.view];
    //在View中的移动量 以手指按下的为原点
    CGPoint point1=[pan translationInView:self.navigationController.view];
    if (pan.state==UIGestureRecognizerStateChanged&&pan==_panGestureRecognizer) {

        if (point1.x>0&&self.navigationController.view.frame.origin.x<self.navigationController.view.frame.size.width-100) {
            //下面if主要是解决tableView滑动会引起navigationController.View也滑动的bug
            if (point1.x<50&&self.navigationController.view.frame.origin.x==0) {
                return;
            }
            float x= self.navigationController.view.frame.origin.x+point1.x>self.navigationController.view.frame.size.width-100?self.navigationController.view.frame.size.width-100:self.navigationController.view.frame.origin.x+point1.x;
            self.navigationController.view.frame=CGRectMake(x, self.navigationController.view.frame.origin.y, self.navigationController.view.frame.size.width, self.navigationController.view.frame.size.height);
            NSLog(@"%@",NSStringFromCGRect(self.navigationController.view.frame));
        }
        else if(point1.x<0)
        {
            NSLog(@"aaa  %f",self.navigationController.view.frame.origin.x);
            float x=self.navigationController.view.frame.origin.x+point1.x<0?0:self.navigationController.view.frame.origin.x+point1.x;
            self.navigationController.view.frame=CGRectMake(x, self.navigationController.view.frame.origin.y, self.navigationController.view.frame.size.width, self.navigationController.view.frame.size.height);
        }
    }
    else if(pan.state==UIGestureRecognizerStateEnded)
    {

        if (self.navigationController.view.frame.origin.x>self.navigationController.view.frame.size.width/3) {
            [UIView animateWithDuration:0.2 animations:^{
                self.navigationController.view.frame=CGRectMake(self.navigationController.view.frame.size.width-100, 0, self.navigationController.view.frame.size.width, self.navigationController.view.frame.size.height);
            } completion:^(BOOL finished) {
                 self.bottomScrollView.scrollEnabled=YES;
            }];
        }
        else
        {
            [UIView animateWithDuration:0.2 animations:^{
                self.navigationController.view.frame=CGRectMake(0, 0, self.navigationController.view.frame.size.width, self.navigationController.view.frame.size.height);
            } completion:^(BOOL finished) {
                self.bottomScrollView.scrollEnabled=YES;
            }];

        }
    }
    //偏移量是增加的应该设为0
    [pan setTranslation:CGPointZero inView:self.navigationController.view];
}

4.手势冲突解决

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
    if (self.bottomScrollView.contentOffset.x<=0.0&&gestureRecognizer==_panGestureRecognizer) {
        if (self.navigationController.view.frame.origin.x>0) {
           self.bottomScrollView.scrollEnabled=NO;
        }
        else
        {
            self.bottomScrollView.scrollEnabled=YES;

        }
        return YES;
    }
    return NO;
}

四、效果图