Hiding Tableview section headers on the fly - ios

Question

I am trying to hide and display section headers when there is or isn't data populating the tableview. The code I have now works as intended occasionally, but mostly, one or both of the section headers will remain displayed, (However, if I drag the header off screen when there is no data it will disappear as intended).
This is the code I am using to hide/unhide the sections.
-(UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section {
//Create custom header titles for desired header spacing
if (section == 0) {
UIView *headerView;
if (self.searchUsers.count || self.searchTracks.count)
{
headerView = [[UIView alloc]initWithFrame:CGRectMake(0, 0, 320, 40)];
}
else{
headerView = [[UIView alloc]initWithFrame:CGRectMake(0, 0, 0, 0)];
}
HeaderTitleLabel *headerTitle = [[HeaderTitleLabel alloc] initWithFrame:CGRectMake(17, 10, 150, 20) headerText:#"USERS"];
[headerView addSubview:headerTitle];
return headerView;
}
else if (section == 1){
UIView *headerView;
if (self.searchUsers.count || self.searchTracks.count)
{
headerView = [[UIView alloc]initWithFrame:CGRectMake(0, 0, 320, 40)];
}
else{
headerView = [[UIView alloc]initWithFrame:CGRectMake(0, 0, 0, 0)];
}
HeaderTitleLabel *headerTitle = [[HeaderTitleLabel alloc] initWithFrame:CGRectMake(17, 0, 150, 20) headerText:#"SONGS"];
[headerView addSubview:headerTitle];
return headerView;
}
else
return nil;
}
-(CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section
{
//custom header spacing
if (section == 0) {
if (self.searchUsers.count || self.searchTracks.count)
{
return 40;
}
else
return 0;
}
else if (section == 1) {
if (self.searchUsers.count || self.searchTracks.count)
{
return 50;
}
else
return 0;
}
else
return 0;
}
I check if my array has objects, if not then set the frame's height to 0. This doesn't seem to be working though. Any ideas how I should go about doing this? Thank you.

Answer 1

Your model should drive your table view. Don't just return a 'number of rows' value from your model, but also a 'number of sections' value.
Consider an array that contains two arrays as your model.

Answer 2

You are using wrong approach of table view. Can you clarify what do you exactly want to do. I could help you. Rather then UIView use UITableView Cell.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
if (self.searchUsers.count || self.searchTracks.count)
{
if (indexPath.section ==0) {
static NSString *simpleTableIdentifier = #"CategoryCell";
CategoryCell *cell = (CategoryCell *)[tableView dequeueReusableCellWithIdentifier:simpleTableIdentifier];
if (cell == nil)
{
NSArray *nib = [[NSBundle mainBundle] loadNibNamed:#"CategoryCell" owner:self options:nil];
cell = [nib objectAtIndex:0];
}
cell.lbl_CatName.text = [[self.CategoryArray objectAtIndex:indexPath.row] objectForKey:kNAME];
return cell;}
else if (indexPath.section ==1){
static NSString *EarnPointIdentifier = #"EarnPointTableCell";
EarnPointTableCell *EarnPointcell = (EarnPointTableCell *)[tableView dequeueReusableCellWithIdentifier:EarnPointIdentifier];
if (EarnPointcell == nil)
{
NSArray *nib = [[NSBundle mainBundle] loadNibNamed:#"EarnPointTableCell" owner:self options:nil];
EarnPointcell = [nib objectAtIndex:0];
}
return EarnPointcell ;
}
else{
//it will have transparent background and every thing will be transparent
static NSString *RewardIdentifier = #"RewardTableCell";
RewardTableCell *RewardCell = (RewardTableCell *)[tableView dequeueReusableCellWithIdentifier:RewardIdentifier];
if (RewardCell == nil)
{
NSArray *nib = [[NSBundle mainBundle] loadNibNamed:#"RewardTableCell" owner:self options:nil];
RewardCell = [nib objectAtIndex:0];
}
return RewardCell ;
}
}
}

Answer 3

It seems to be working fine now. What I did was create boolean values to keep track of my data when my data source is nil. Like so;
[SoundCloudAPI getTracksWithSearch:userInput userID:nil withCompletion:^(NSMutableArray *tracks) {
self.searchTracks = tracks;
[self.tableView beginUpdates];
if (tracks.count) {
self.songsHeaderIsHidden = NO;
}
else
self.songsHeaderIsHidden = YES;
[self.tableView reloadSections:[NSIndexSet indexSetWithIndex:1] withRowAnimation:UITableViewRowAnimationFade];
[[self.tableView headerViewForSection:1] setNeedsLayout];
[[self.tableView headerViewForSection:1] setNeedsDisplay];
[self.tableView endUpdates];
}];
Then set the header accordingly..
-(UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section {
//Create custom header titles for desired header spacing
if (section == 0) {
if (self.userHeaderIsHidden) {
return nil;
}
else {
UIView *userHeaderView = [[UIView alloc]initWithFrame:CGRectMake(0, 0, 320, 40)];
HeaderTitleLabel *usersHeaderTitle = [[HeaderTitleLabel alloc] initWithFrame:CGRectMake(17, 10, 150, 20) headerText:#"USERS"];
[userHeaderView addSubview:usersHeaderTitle];
return userHeaderView;
}
}
else if (section == 1){
if (self.songsHeaderIsHidden) {
return nil;
}
else {
UIView *songsHeaderView = [[UIView alloc]initWithFrame:CGRectMake(0, 0, 320, 40)];
songsHeaderView = [[UIView alloc]initWithFrame:CGRectMake(0, 0, 320, 40)];
HeaderTitleLabel *songsHeaderTitle = [[HeaderTitleLabel alloc] initWithFrame:CGRectMake(17, 0, 150, 20) headerText:#"SONGS"];
[songsHeaderView addSubview:songsHeaderTitle];
return songsHeaderView;
}
}
else
return nil;
}

Answer 4

Personally, I would use UICollectionView and write your own layout. That way you can explicitly layout where the section headers will be at all times. The best approach is to probably subclass UICollectionViewFlowLayout because you get all the superclass properties for free (such as itemSize, headerReferenceSize, etc.)
Here's an implementation I wrote for having sticky headers, like the Instagram app.
Notice that in prepareLayout, I just calculate the normal positions of every element. Then in layoutAttributesForElementInRect I go through and figure out where to place the header. This is where you can go through and see if the header should be shown or not.
import UIKit
class BoardLayout: UICollectionViewFlowLayout {
private var sectionFrames: [CGRect] = []
private var headerFrames: [CGRect] = []
private var footerFrames: [CGRect] = []
private var layoutAttributes: [UICollectionViewLayoutAttributes] = []
private var contentSize: CGSize = CGSizeZero
override func prepareLayout() {
super.prepareLayout()
self.sectionFrames.removeAll(keepCapacity: false)
self.headerFrames.removeAll(keepCapacity: false)
self.footerFrames.removeAll(keepCapacity: false)
self.layoutAttributes.removeAll(keepCapacity: false)
let sections = self.collectionView?.numberOfSections()
var yOffset: CGFloat = 0.0
for var i: Int = 0; i < sections; i++ {
let indexPath = NSIndexPath(forItem: 0, inSection: i)
var itemSize: CGSize = self.itemSize
if let d = self.collectionView?.delegate as? UICollectionViewDelegateFlowLayout {
if let collection = self.collectionView {
if let size = d.collectionView?(collection, layout: self, sizeForItemAtIndexPath: NSIndexPath(forItem: 0, inSection: i)) {
itemSize = size
}
}
}
let headerFrame = CGRect(x: 0, y: yOffset, width: self.headerReferenceSize.width, height: self.headerReferenceSize.height)
self.headerFrames.append(headerFrame)
var headerAttribute = UICollectionViewLayoutAttributes(forSupplementaryViewOfKind: UICollectionElementKindSectionHeader, withIndexPath: indexPath)
headerAttribute.frame = headerFrame
headerAttribute.zIndex = 1000
self.layoutAttributes.append(headerAttribute)
yOffset += self.headerReferenceSize.height - 1 // - 1 so that the bottom border of the header and top border of the cell line up
let sectionFrame = CGRect(x: 0, y: yOffset, width: itemSize.width, height: itemSize.height)
self.sectionFrames.append(sectionFrame)
var sectionAttribute = UICollectionViewLayoutAttributes(forCellWithIndexPath: indexPath)
sectionAttribute.frame = sectionFrame
self.layoutAttributes.append(sectionAttribute)
yOffset += itemSize.height
let footerFrame = CGRect(x: 0, y: yOffset, width: self.footerReferenceSize.width, height: self.footerReferenceSize.height)
self.footerFrames.append(footerFrame)
var footerAttribute = UICollectionViewLayoutAttributes(forSupplementaryViewOfKind: UICollectionElementKindSectionFooter, withIndexPath: indexPath)
footerAttribute.frame = footerFrame
self.layoutAttributes.append(footerAttribute)
yOffset += self.minimumLineSpacing + self.footerReferenceSize.height
}
self.contentSize = CGSize(width: self.collectionView!.width, height: yOffset)
}
override func layoutAttributesForElementsInRect(rect: CGRect) -> [AnyObject]? {
var newAttributes: [UICollectionViewLayoutAttributes] = []
for attributes in self.layoutAttributes {
let frame = attributes.frame
if !CGRectIntersectsRect(frame, CGRect(x: 0, y: rect.origin.y, width: rect.size.width, height: rect.size.height)) {
continue
}
let indexPath = attributes.indexPath
let section = indexPath.section
if let kind = attributes.representedElementKind {
if kind == UICollectionElementKindSectionHeader {
var headerFrame = attributes.frame
let footerFrame = self.footerFrames[section]
if CGRectGetMinY(headerFrame) <= self.collectionView!.contentOffset.y {
headerFrame.origin.y = self.collectionView!.contentOffset.y
}
if CGRectGetMinY(headerFrame) >= CGRectGetMinY(footerFrame) {
headerFrame.origin.y = footerFrame.origin.y
}
attributes.frame = headerFrame
self.headerFrames[section] = headerFrame
} else if kind == UICollectionElementKindSectionFooter {
attributes.frame = self.footerFrames[section]
}
} else {
attributes.frame = self.sectionFrames[section]
}
newAttributes.append(attributes)
}
return newAttributes
}
override func layoutAttributesForItemAtIndexPath(indexPath: NSIndexPath) -> UICollectionViewLayoutAttributes! {
let frame = self.sectionFrames[indexPath.item]
let attributes = super.layoutAttributesForItemAtIndexPath(indexPath)
attributes.frame = frame
return attributes
}
override func layoutAttributesForSupplementaryViewOfKind(elementKind: String, atIndexPath indexPath: NSIndexPath) -> UICollectionViewLayoutAttributes! {
let attributes = super.layoutAttributesForSupplementaryViewOfKind(elementKind, atIndexPath: indexPath)
if elementKind == UICollectionElementKindSectionHeader {
attributes.frame = self.headerFrames[indexPath.section]
} else if elementKind == UICollectionElementKindSectionFooter {
attributes.frame = self.footerFrames[indexPath.section]
}
return attributes
}
override func collectionViewContentSize() -> CGSize {
return self.contentSize
}
override func shouldInvalidateLayoutForBoundsChange(newBounds: CGRect) -> Bool {
return true
}
}
I'd recommend using the UICollectionViewDelegateFlowLayout methods so you can dynamically determine the reference size of the header.