UIScrollView按需加载控制器

前言

现在标签分页横向滚动控制器很普遍，自己写原生的需要一些细节注意。
我们都知道一次请求不要太多，所以按照滚动到某处位置在显示加载就很有必要。

代码

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
    
    int index = floor((scrollView.contentOffset.x - SCREEN_WIDTH / 2) / SCREEN_WIDTH) + 1;
    self.topView.selectIndex = index;
    if (index < self.store.homeMenuArray.count) {
        LiveHomeMenuModel *model = self.store.homeMenuArray[index];
        NSString *title = model.name;
        if ([title isEqualToString:@"视频"]) {
            self.publishButton.hidden = YES;
        }else {
            self.publishButton.hidden = NO;
        }
        if ([title isEqualToString:@"秘密"]){
            self.publishButton.selected = YES;
        }else {
            self.publishButton.selected = NO;
        }
        UIViewController *vc = self.itemControllerArray[index];
        if (!vc.isViewLoaded) {
            vc.view.frame = CGRectMake(SCREEN_WIDTH *index, 0, SCREEN_WIDTH, self.contentHeight);
            [self.scrollView addSubview:vc.view];
            [self addChildViewController:vc];
        }
    }
}