iOS新闻列表以及栏目订阅，cell嵌套控制器

1.效果:

1.gif 2.gif 3.gif 4.gif 5.gif 6.gif 7.gif 8.gif

2.概要：

这个组件主要是我项目中使用的，拿出来就开源了，可能封装性并不是很强，因为好的封装需要很多附加代码，个人不太喜欢干这个。所以你想拿来直接用也是可以的，代码里面写了很多演示用法。这个组件最主要的目的是提供一种实现方式，而这种方式核心代码量相对较少，易于学习和自己扩展实现，这才是本项目的核心。

3.实现：

XQPageController分页控制器组件主要使用了系统的组件UIPageViewController，在此组件的基础上添加每个栏目的控制器，每个控制器可以单独管理自己，也有很多“网易新闻”栏目是使用一个外部控制器里面嵌套控制器，这些子控制器时添加在自定义的scrollview上的，比如WMPageControllerDemo

1.实现数据源代理方法UIPageViewControllerDataSource，通过子类协议[self.dataSource viewcontrollerWithIndex:index]实现返回对应的控制器方法，在数据源返回对应控制器

- (UIViewController *)pageViewController:(UIPageViewController *)pvc viewControllerBeforeViewController:(UIViewController *)vc {
    NSInteger index = self.nextIndex - 1;
    return [self controllerWithIndex:index];
}

- (UIViewController *)pageViewController:(UIPageViewController *)pvc viewControllerAfterViewController:(UIViewController *)vc {
    NSInteger index = self.nextIndex + 1;
    return [self controllerWithIndex:index];
}

- (UIViewController *)controllerWithIndex:(NSInteger)index {
    if (index < [titles count] && index >= 0) {
        UIViewController *controller = [self.dataSource viewcontrollerWithIndex:index];
        controller.index = index;
        controller.pageDelegate = self;
        return controller;
    }
    return nil;
}

2.UIPageViewControllerDelegate代理方法返回UIPageViewController对应的index，以及下一个index和变换状态等

- (void)pageViewController:(UIPageViewController *)pageViewController willTransitionToViewControllers:(NSArray<UIViewController *> *)pendingViewControllers {
    self.inTransition = YES;
    self.nextIndex = pendingViewControllers[0].index;
    if ([self.dataSource respondsToSelector:@selector(pageViewController:willTransitionToViewControllers:)] && ![self isEqual:self.dataSource]) {
        [self.dataSource pageViewController:pageViewController willTransitionToViewControllers:pendingViewControllers];
    }
}

- (void)pageViewController:(UIPageViewController *)pageViewController didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray<UIViewController *> *)previousViewControllers transitionCompleted:(BOOL)completed {
    self.inTransition = NO;
}

- (void)pageViewController:(id<ScrollPageViewControllerProtocol>)pageViewController didShowViewController:(UIViewController *)controller atIndex:(NSInteger)index {
    self.nextIndex = NSNotFound;
    self.currentIndex = index;
    if ([self.dataSource respondsToSelector:@selector(pageViewController:didShowViewController:atIndex:)] && ![self.dataSource isEqual:self]) {
        [self.dataSource pageViewController:pageViewController didShowViewController:controller atIndex:index];
    }
}

3.还有上面的menuBar视图，这里使用的是FDSlideBar，对代码进行的稍微的修改。添加到UIPageViewController上。

4.最主要的一点，协同控制
当滑动pagecontroller的时候，slidebar需要做相应的item切换，点击slidebar的时候，pagecontroller也要切换到对应的位置。

先说滑动pagecontroller的时候：
通过UIPageViewControllerDelegate获取index，通过UIPageViewControlle的scrollview获取偏移量，更改slidebar的frame
同时，监听currentindex的改变，切换slidebar的item

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSString *, id> *)change context:(void *)context {
    if ([keyPath isEqualToString:@"currentIndex"]) {
        NSUInteger changenew = [change[@"new"] integerValue];
        NSUInteger changeold = [change[@"old"] integerValue];
        if (changeold != changenew) {
            [self.slideBar selectSlideBarItemAtIndex:changenew];
        }
    }
}

接下来看是slidebar改变pagecontroller的实现，在slidebar里增加回调方法，回调currentIndex，然后pagecontroller切换到对应位置

- (void)setupSlideBar {
    FDSlideBar *slide = self.slideBar;
    slide.backgroundColor = [UIColor whiteColor];
    slide.itemColor = [UIColor blackColor];
    slide.itemSelectedColor = [UIColor redColor];
    slide.sliderColor = [UIColor redColor];
    slide.showMenuButton = _showMore;
    slide.menuButtonSelectedTitleColor = [UIColor colorWithWhite:.5 alpha:1];
    slide.menuButtonImage = [UIImage imageNamed:@"gonggao_customized.png"];
    slide.menuButtonSelectedImage = [UIImage imageNamed:@"gonggao_customized.png"];
    slide.menuButtonTitleColor = [UIColor colorWithWhite:0.5 alpha:1];
    // callBack
    __weak typeof(self) weakSel = self;
    [slide slideBarItemSelectedCallback:^(NSUInteger idx) {
        if (idx != weakSel.currentIndex) {
            [weakSel setToIndex:idx];
        }
    }];
}

/// 切换到某个index
- (void)setToIndex:(NSInteger)index {
    self.nextIndex = NSNotFound;
    if ([titles count]) {
        // 判断index，防止传入异常数据导致角标越界
        if (index >= [titles count]) index = [titles count] - 1;
        if (index < 0) index = 0;
        
        __weak typeof(self) weakSelf = self;
        UIViewController *list = [self controllerWithIndex:index];
        [self.pageViewController setViewControllers:@[list] direction:(index > self.currentIndex ?UIPageViewControllerNavigationDirectionForward : UIPageViewControllerNavigationDirectionReverse) animated:YES completion:^(BOOL finished){
            weakSelf.currentIndex = index;
        }];
    }
}

主要的讲完了，剩下的就是一些琐碎的补充了，具体看代码
代码:XQPageController