tableView 小技巧

1.tableview section头部不悬停
正常section不为0的时候，section的headerView会悬停在当前视图中，如QQ
解决办法

#pragma mark -- 头部悬停
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
    CGFloat sectionHeaderHeight = kViewHeightScaleOf6s(97);
    if (scrollView.contentOffset.y <= sectionHeaderHeight && scrollView.contentOffset.y >= 0) {
        scrollView.contentInset = UIEdgeInsetsMake(-scrollView.contentOffset.y, 0, 0, 0);
    } else if (scrollView.contentOffset.y >= sectionHeaderHeight) {
        scrollView.contentInset = UIEdgeInsetsMake(-sectionHeaderHeight, 0, 0, 0);
    }
}

2.tableView系统选中方法

self.tableview.allowsMultipleSelectionDuringEditing = YES;
self.tableview.editing = YES;

3.mj上拉加载重复加载问题

UIScrollView (MJRefresh)

- (void)setMj_footer:(MJRefreshFooter *)mj_footer
{
    if (mj_footer != self.mj_footer) {
        // 删除旧的，添加新的
        [self.mj_footer removeFromSuperview];
        [self insertSubview:mj_footer atIndex:0];
   // ios11 适配 关闭self-sizing
        if ([self isKindOfClass:[UITableView class]]) {
            UITableView *view = (UITableView *)self;
            view.estimatedRowHeight = 0;
            view.estimatedSectionHeaderHeight = 0;
            view.estimatedSectionFooterHeight = 0;
        }
        // 存储新的 
    [self willChangeValueForKey:@"mj_footer"]; // KVO
        objc_setAssociatedObject(self, &MJRefreshFooterKey,
                                 mj_footer, OBJC_ASSOCIATION_ASSIGN);
        [self didChangeValueForKey:@"mj_footer"]; // KVO
    }
}

4.ios11 用到tableview headerview 的时候需要用到下面的预估代码, 不用的话会出错

if (@available(iOS 11.0,*)) {
        [UIScrollView appearance].contentInsetAdjustmentBehavior = UIScrollViewContentInsetAdjustmentNever;
        
        //解决iOS11，仅实现heightForHeaderInSection，没有实现viewForHeaderInSection方法时,section间距大的问题
        [UITableView appearance].estimatedRowHeight = 0;
        [UITableView appearance].estimatedSectionHeaderHeight = 0;
        [UITableView appearance].estimatedSectionFooterHeight = 0;
}else{
        self.automaticallyAdjustsScrollViewInsets = NO;
    }

5.iphone_X适配：

// 判断是否是iPhone X
#define iPhoneX ([UIScreen instancesRespondToSelector:@selector(currentMode)] ? CGSizeEqualToSize(CGSizeMake(1125, 2436), [[UIScreen mainScreen] currentMode].size) : NO)
// 导航栏高度
#define KNAVIGATION_BAR_HEIGHT (iPhoneX ? 88.f : 64.f)
// 状态栏高度
#define KSTATUS_BAR_HEIGHT (iPhoneX ? 44.f : 20.f)
// tabBar高度
#define KTAB_BAR_HEIGHT (iPhoneX ? (83.f) : 49.f)
// 底部的高度
#define KBOTTOM_HEIGHT (iPhoneX ? 34.f : 0.f)