Custom View add SubView layout issue - ios

Question

There is a tableView with 2 sections, which have a customized section header view for each.
I want UI of this effect, and header view of section 0 works fine.
While header view of section 1 has an issue.
I don't know what's wrong.
What Apple mechanism do I miss,
convert rect/point?
Here is the code:
the customized view of section 1
#interface ZBWithDrawHeaderView()
#property (nonatomic, strong ) UIView *renderView;
#end
#implementation ZBWithDrawHeaderView
- (instancetype)initWithFrame:(CGRect)frame{
if (self = [super initWithFrame:frame]) {
self.backgroundColor = [UIColor grayColor ];
_renderView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, KScreenWidth, -17)];
//it works OK, I don't know the logic.
// _renderView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, KScreenWidth, 17)];
//it works Wrong ,what mechanism do I miss
[self addSubview: _renderView];
_renderView.backgroundColor = [UIColor redColor ];
}
return self;
}
#end
Where I put it into use?
- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section{
if(section == 0){
......
return view;
}
else if (section == 1) {
ZBWithDrawHeaderView * secondHeaderView = [[ZBWithDrawHeaderView alloc] initWithFrame: CGRectMake(0, 0, KScreenWidth, 25)];
return secondHeaderView;
}
return nil;
}

Answer 1

- (CGFloat)tableView:(UITableView *)tableView heightForFooterInSection:(NSInteger)section{
return CGFLOAT_MIN;
}
- (UIView *)tableView:(UITableView *)tableView viewForFooterInSection:(NSInteger)section{
return [UIView new ];
}
The two UITableViewDelegate methods added, no strange layout happens. Seems like section header and footer must come in pair.