I want cellForRowAtIndexPath to be always called even if numberOfRowsInSection ==0 as i'm hiding and showing a section inside the table by setting numberOfRowsInSection to zero but when i do that the method stated above doesn't executed as numberOfRowsInSection becomes zero which makes a problem as the contents of the cell remains rendered although the section header disappears, any idea on how to hide the contents of the cell after setting the numberOfRowsInSection to zero:
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
if (section==0||section==1)
return 1;
if (section==2) {
if (self.isSectionAppears)
return 1;
else
return 0;
}
}
given that self.isSectionAppears is a bool property setted to false when i want to hide the section
You shouldn't be burying your section showing/hiding logic in your cellForRowAtIndexPath. When you need to tell the tableview to update the section header, you can do a refresh on the section with the code
NSUInteger sectionToRefresh = //index of table section with header you want to refresh.
NSIndexSet indexSetWithSection = [NSIndexSet indexSetWithIndex:sectionToRefresh];
[tableView reloadSections:indexSetWithSection withRowAnimation:UITableViewRowAnimationAutomatic];
If you'd like to refresh visual elements of your section header without refreshing the rest of the section, you could do so by acting on your section header object directly:
//Get section header from table
UITableViewHeaderFooterView* myHeader = [tableView headerViewForSection:sectionToRefresh];
//Update header
[myHeader.textLabel setText:newSectionHeaderText]; //Update it's text for example.
Related
I have a UITableViewController, with its table view having static cells, defined in a storyboard.
My table view has two sections. The first with two cells, and the second section has three cells. The second section also has text in its header.
What I would like to do is that when the user taps the first or second cells in the first section, to update the header text of the second section. Do so dynamically and with dynamic content (say the date and time is displayed there as of the moment they tap cells).
I have tried numerous things, but the viewForHeaderSection is only called once.
I registered the header section cell with
tableView.registerClass(TableSectionHeader.self, forHeaderFooterViewReuseIdentifier: "secondSectionCell")
Where TableSectionHeader is simply:
class TableSectionHeader: UITableViewHeaderFooterView { }
I am then able to dynamically set the section header, like so:
override func tableView(tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
if section == 1 {
if let cell = tableView.dequeueReusableHeaderFooterViewWithIdentifier("secondSectionCell") {
cell.textLabel?.text = "hello world"
return cell
}
}
return nil
}
I also have implemented the following override, since some people suggest that when implementing viewForHeaderInSection, it is also required:
override func tableView(tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
return 40.0
}
Even still. viewForHeaderInSection is only called once.
Am I able to somehow refresh the section header text dynamically as described above?
You can actually achieve this using traditional table view way easily.
Even though it is static UITableView, in your dataSource view controller, you can still implement - (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
So how do you update the title on the fly? Create a property for this view controller, say NSString *titleForSecondSection. Whenever user tap the cells in the first section, you just need to update this property in the callback - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
The last step is to call [self.tableView reload] after you modified the titleForSecondSection property. Or if you don't want to reload the whole table view, just call - (void)reloadSections:(NSIndexSet *)sections withRowAnimation:(UITableViewRowAnimation)animation
To be clear, in your - (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section, for sections that don't need to change title, just return a static string. For sections that need to change title, return the dynamic property you created.
viewForHeaderInSection would only be called when the tableview is reloaded. So assuming you don't want to reload the whole tableview, you might need to change the content of label directly.
pseudo codes like:
var label_first_section_header //as global variable
then in viewForHeaderInSection just point it to the label
if section == 1 {
if let cell = tableView.dequeueReusableHeaderFooterViewWithIdentifier("secondSectionCell") {
cell.textLabel?.text = "hello world"
label_first_section_header = cell.textLabel
return cell
}
}
then you can change the text dynamically whenever you want, for example in didSelectRowAtIndexPath
I am able to expand and collapse the tableView sections successfully however I am not able to do it for individual sections so far.So all the sections collapse or expand at the same time.
You can collapse and expand tableView section by removing and adding tableViewCells on demand, like if you want to collapse reload that tableViewSection data and return zero in numberOfRowsInSection, and when you want to expand it back just return right amount of rows from numberOfRowsInSection method, it should be something like below
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
//Check if section is collapsed
if (section_is_collapsed) return 0;
return actual_num_of_rows_in_Section;
}
In my iOS app, I have a UITextView inside a tableview cell.
The UITextView and hence the cell height expands when the frame required for the text entered by user exceeds the current height of the cell.
In order to achieve the above, I am calling [tableView beginUpdates] followed by [tableView endUpdates] to reload the height for the cells.
The above is resulting duplicate section headers overlapping the expanded cell.
Is there a way to fix this without calling [tableView reloadData]?
Appended below is some relevant code:
When there is a text change, I verify if the text will fit in current text view, if not the cell is expanded to the new height:
- (void)textViewDidChange:(UITextView *)textView {
CGFloat oldTextViewHeight = [(NSNumber *)[self.cachedTextViewHeightsDictionary objectForKey:indexPath] floatValue];
CGFloat newTextViewHeight = [textView sizeThatFits:CGSizeMake(textView.frame.size.width, CGFLOAT_MAX)].height + CELL_HEIGHT_PADDING;
if (newTextViewHeight > oldTextViewHeight ||
(newTextViewHeight != oldTextViewHeight && oldTextViewHeight != TEXTVIEW_CELL_TEXTVIEW_HEIGHT)) {
[self reloadRowHeights];
}
}
- (void)reloadRowHeights {
// This will cause an animated update of the height of the UITableViewCell
[self.tableView beginUpdates];
[self.tableView endUpdates];
}
It's also important to note that I am using a custom section header, which makes my problem similar to one mentioned here:
UITableView Custom Section Header, duplicate issue
I cannot however use the solution to above problem because I cannot reloadData for the tableView in middle of user entering text.
Try implementing
tableView(_ tableView: UITableView, estimatedHeightForHeaderInSection section: Int)
delegate method if you didn't
Little late to the party, but I couldn't find a working solution on SO, and then I figured one out, so I thought I'd share.
I use UITableViewAutomaticDimension both for cell heights and for section header heights. My header view class is just a UIView subclass with some subviews as needed. Inside my tableView(:viewForHeaderInSection:) class, I just initialized a new header view as needed, and I was experiencing this duplicate headers issue. Not even reloadData helped.
What seems to have fixed it for me was to implement basic "cell re-use" for the headers. Something like this:
Store the header views in a dictionary somewhere in your view controller.
class ViewController: UIViewController {
var sectionHeaders: [Int: UIView] = [:]
// etc...
}
Then, upon request, return your existing section header view if available, or else create and store a new one.
func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
if let sectionHeader = self.sectionHeaders[section] {
return sectionHeader
} else {
let sectionHeader = YourSectionHeader()
// Setup as needed...
self.sectionHeaders[section] = sectionHeader
return sectionHeader
}
}
I have an auto populating UITableView from a NSMutableArray. I need to add a static cell to the top of the table from a prototype I built in storyboard. What is the correct way of doing this?
When I just added the prototype to the storyboard editor, it started out by covering up the first cell. After reloading the data, it would eventually appear under the other cells.
To make "space" for it, I made the table "editable" with the following code -
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
return self.editing ? wOutputArray.count + 1 : wOutputArray.count;
}
Now it doesn't cover any cells, but it seems as though it doesn't have a home. At initial view load it's at the top of the table, then after a few refreshes it eventually falls back to the bottom of the table.
EDIT:
I'm reading that you can't mix static cells with dynamic cells, and that the table should be split up into sections.
So here I changed-
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableViewB{
return 2;
}
&
- (NSInteger)tableView:(UITableView *)tableViewB numberOfRowsInSection:(NSInteger)section{
switch(section){
case 0:
return 1;
break;
case 1:
return wOutputArray.count;
break;
}
return 0;
}
But I'm not sure what to do next... Is this the right direction?
Technically, both types of cells that you want to use are prototype cells - they are just different types of cell.
If you just want a static cell at the top of the others then all you need to do is account for it in your table data source methods.
First let the tableview know that there will 1+(dynamic cells count) cells
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
return wOutputArray.count + 1
}
Second, in cellForRowAtIndexPath return the appropriate cell, accounting for the fact that indexPath.row will be 1 more than the element of your array (because row 0 is the static cell)
func tableView(tableView: UITableView!, cellForRowAtIndexPath indexPath: NSIndexPath!) -> UITableViewCell! {
var cell
if (indexPath.row==0) {
cell=tableView.dequeueReuseableCellWithIdentifier("staticCell",forIndexPath:indexPath)
// Any other manipulation as required
}
else {
cell=tableView.dequeueReuseableCellWithIdentifier("dynamicCell",forIndexPath:indexPath)
cell.label.text=wOutputArray[indexPath.row-1]; // Or whatever property you want to use
}
return cell!
}
I have the following implemented:
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{ return 75; }
The height is displaying properly only when it receives json serialization data. When it is getting no data, it displays the height as the default height. What is overriding this method?
If you want every row to be the same height then don't use the tableView:heightForRowAtIndexPath: method.
Instead, set the table view row height once, in viewDidLoad:
self.tableView.rowHeight = 75;
This will work for all rows, not just the ones with data.
The method heightForRowAtIndexPath only called when numberOfRowsInSection return value > 0. In this case what you saw is the default empty table view.
I think in the case you have no data, you should hide all the default empty row by this line of code in viewDidLoad:
tableView.tableFooterView = [UIView new];
And show and empty Label of Image to let user know no data returned. Example:
- (void) requestData {
// Your request data code
// When request data complete, check and show that label
self.labelNoData.hidden = (arrayData.count == 0);
}