Problem:
I would like to limit the amount of cells shown. For example, 100.
Once the tableView has reached the bottom I would like to extend that limit further since the data is already there, I do not need an activity loader.
I simply would like to tableView refresh and exceed the minimum of 100 in a smooth manner
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if(delegate.groupedSessions[section].count > 100){
return 100
}else{
return delegate.groupedSessions[section].count
}
}
Pseudocode:
(If scrolled to bottom or indexPath.row >= 100)
Exceed numberOfRowsInSection limit to 200 and so on.
let increment = 100
var limit == 100
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
// Not sure how your code is set up or what "delegate" is but I'm assuming that's your model that holds the data
if limit < delegate.groupedSessions[section].count {
return limit
} else {
return delegate.groupedSessions[section].count
}
}
// This is a Delegate Method
func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
guard indexPath.row == limit - 1 else { return }
limit += increment
tableView.reloadData()
}
I'm also not sure what you're trying to achieve. Even if you do this, the tableview would just keep scrolling smoothly like the limits weren't even there. But you asked, so.
Related
I'm implementing collapsable section headers in a UITableViewController.
Here's how I determine how many rows to show per section:
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int
{
return self.sections[section].isCollapsed ? 0 : self.sections[section].items.count
}
There is a struct that holds the section info with a bool for 'isCollapsed'.
Here's how I'm toggling their states:
private func getSectionsNeedReload(_ section: Int) -> [Int]
{
var sectionsToReload: [Int] = [section]
let toggleSelectedSection = !sections[section].isCollapsed
// Toggle collapse
self.sections[section].isCollapsed = toggleSelectedSection
if self.previouslyOpenSection != -1 && section != self.previouslyOpenSection
{
self.sections[self.previouslyOpenSection].isCollapsed = !self.sections[self.previouslyOpenSection].isCollapsed
sectionsToReload.append(self.previouslyOpenSection)
self.previouslyOpenSection = section
}
else if section == self.previouslyOpenSection
{
self.previouslyOpenSection = -1
}
else
{
self.previouslyOpenSection = section
}
return sectionsToReload
}
internal func toggleSection(_ header: CollapsibleTableViewHeader, section: Int)
{
let sectionsNeedReload = getSectionsNeedReload(section)
self.tableView.beginUpdates()
self.tableView.reloadSections(IndexSet(sectionsNeedReload), with: .automatic)
self.tableView.endUpdates()
}
Everything is working and animating nicely, however in the console when collapsing an expanded section, I get this [Assert]:
[Assert] Unable to determine new global row index for preReloadFirstVisibleRow (0)
This happens, regardless of whether it's the same opened Section, closing (collapsing), or if I'm opening another section and 'auto-closing' the previously open section.
I'm not doing anything with the data; that's persistent.
Could anyone help explain what's missing? Thanks
In order for a tableView to know where it is while it's reloading rows etc, it tries to find an "anchor row" which it uses as a reference. This is called a preReloadFirstVisibleRow. Since this tableView might not have any visible rows at some point because of all the sections being collapsed, the tableView will get confused as it can't find an anchor. It will then reset to the top.
Solution:
Add a 0 height row to every group which is collapsed. That way, even if a section is collapsed, there's a still a row present (albeit of 0px height). The tableView then always has something to hook onto as a reference. You will see this in effect by the addition of a row in numberOfRowsInSection if the rowcount is 0 and handling any further indexPath.row calls by making sure to return the phatom cell value before indexPath.row is needed if the datasource.visibleRows is 0.
It's easier to demo in code:
func numberOfSections(in tableView: UITableView) -> Int {
return datasource.count
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return datasource[section].visibleRows.count == 0 ? 1 : datasource[section].visibleRows.count
}
func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
datasource[section].section = section
return datasource[section]
}
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
if datasource[indexPath.section].visibleRows.count == 0 { return 0 }
return datasource[indexPath.section].visibleRows[indexPath.row].bounds.height
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
if datasource[indexPath.section].visibleRows.count == 0 { return UITableViewCell() }
// I've left this stuff here to show the real contents of a cell - note how
// the phantom cell was returned before this point.
let section = datasource[indexPath.section]
let cell = TTSContentCell(withView: section.visibleRows[indexPath.row])
cell.accessibilityLabel = "cell_\(indexPath.section)_\(indexPath.row)"
cell.accessibilityIdentifier = "cell_\(indexPath.section)_\(indexPath.row)"
cell.showsReorderControl = true
return cell
}
Hello,
i have created a UITableView in which it has two different cells DynamicFormCell and StaticFormCell, so the DynamicFormCell can be displayed number of times i have a data from a server telling me how many forms i need for the DynamicFormCell and the StaticFormCell is always the same and doesn't change so i am having difficulty giving different number of rows for each cell.i tried giving the two cell a tag of 0 and 1 respectively and used this code:
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if(tableView.tag == 0){
return 5//return five dynamic cells
}
if(tableView.tag == 1){
return 1//return one static cell
}
}
but this doesn't work and i also tried removing all the tags and if statements in the above code and just doing this return 5 this just gave me one DynamicFormCell and five StaticFormCells.
i also gave different classes for the two cells so i can assign them separately:
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
if(indexPath.row == 0){
//firstRow make dynamic
let cell = tableView.dequeueReusableCell(withIdentifier: "DynamicFormsCell") as! DynamicFormsCell
return cell
}else{
//static form data
let cell = tableView.dequeueReusableCell(withIdentifier: "StaticFormsCell") as! StaticFormsCell
return cell
}
}
so my question is, is it possible to do this using table views and how can i do it? if not what other options do i have?
Yes it is possible to have multiple types of cell in single tableview. It has nothing to do with function
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int
You should return there cells as,
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return (count of dynamic cells + count of static cells)
}
I assume, you only have to display static cells in the bottom. So if there are total 5 cells then 4 cells are dynamic and 5th cell would be static.
So code for, cellForRowAt indexPath: will be,
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
if(indexPath.row < (count for dynamic cells)){
//first 4 Rows make dynamic
let cell = tableView.dequeueReusableCell(withIdentifier: "DynamicFormsCell") as! DynamicFormsCell
return cell
}else{
//last row static form data
let cell = tableView.dequeueReusableCell(withIdentifier: "StaticFormsCell") as! StaticFormsCell
return cell
}
}
What you're doing right now is checking if the TableView's tag is 0 or 1. Which is not you want to do, since you're using only one TableView.
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return (amount of DynamicCellsYouWant + amount of StaticCellsYouWant)
}
The second part of your code only works when you want the first cell to be a DynamicFormsCell and the rest to be a StaticFormsCell.
Basically I have a view controller with a static table view with 2 sections. The first section will have 1 row and represent a main category.
I want the second section to have a variable amount of rows depending on how many entries the user has for that category. So if the category is "Activities" and they have "Baseball, softball" as activities, I want there to be 2 rows in that section.
How do you do this? It keeps crashing when I code it.
You can try this.....
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if section == 0 {
return 1
} else {
return YourDataSource.count
}
}
and on your cellforrowatindex
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
if indexPath.section == 0 {
//Do your stuff for the static section
} else {
//Do your stuff for the dynamic section
}
}
I need an advice with ViewContoller's scheme. I should create a view with Billing addresses. There can be no address at all, or some addresses. If there no one, there should be only a button "Add New". And if there are addresses, each should have buttons Edit, Remove, and "Add New" too.
I have data for this VC as JSON, parsed and saved to plist.
So what is logic to make this View looks different depends on 1) if there are addresses or not? and 2) if there 1, or 2, or maybe 20 billing addresses?
Thanks a lot!
I solved issues like this with UITableVIew and the UITableViewDataSource and UITableViewDelegate:
setup the table view for one section (adresses)
func numberOfSections(in tableView: UITableView) -> Int {return 1;}
return the address arrays length in the delegate method
func tableView(_ tableView: UITableView, viewForFooterInSection section: Int) -> UIView? {
return adresses.count
}
set the view for footer if the arrays length is 0
func tableView(_ tableView: UITableView, viewForFooterInSection section: Int) -> UIView? {
if adresses.count == 0 {
let vw = YourViewClass()
//I use blockskit library here (vw.bk_) to recognize a tap, but you can add a button by yourself
vw.bk_(whenTapped: {
//Create and present your next viewcontroller to
})
return vw
}
return nil
}
set the footers height to 0 if there are addresses
func tableView(_ tableView: UITableView, heightForFooterInSection section: Int) -> CGFloat {
if addresses.count > 0 {
return YOUR_DESIRED_FOOTER_HEIGHT_FOR_INPUT
}
return 0
}
create row for each address
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let address = addresses[indexPath.row]
let tableViewCell = UITableViewCell() //maybe you have to create your own if the layout does not fit
//set tableViewCell's title / description to show address values
return tableViewCell
}
In this case, the footer view (you can do the same in the header if you want) with the add button is shown when no addresses are available, and it is hidden, when addresses are available.
I have a static grouped table view that has 5 sections (all the sections have headers, no footers). I created all of this using a Storyboard. Now, how can I hide the first/top UITableViewSection (including the header). I tried making an outlet to the UITableViewSection but it tells me that it is not valid (undeclared type):
#IBOutlet var section: UITableViewSection!
I did it this way because I was planning on doing:
section.hidden = true
Can it not be done this way?
My delegates and data sources are set up 100% correctly.
Swift 5:
You can use the delegate method heightForHeaderInSection
:
func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
if (section == 0) {
return 0.0
}
return UITableView.automaticDimension
}
Earlier than Swift 5: Use UITableViewAutomaticDimension instead of UITableView.automaticDimension
If it's not working with height 0.0, use height 0.1
If you want no cells in a particular section, use the delegate method:
func numberOfRowsInSection(section: Int) -> Int {
if (section == 0) {
return 0
}
else {
// return the number of rows you want
}
}
Or to a neater switch-case syntax:
func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
switch section {
case 0:
return 0.0
default:
return UITableView.automaticDimension
}
}
I tested both and they are working fine.
I also wish you could just make an #IBOutlet to a section and hide it, but sadly it seems not, so...
Based on various suggestions here, I've established the following, which doesn't require any interfering with explicit size values, and preserves whatever you may have set on a storyboard/XIB already. It just makes the header nil and row count 0 for any section you want to hide (which results in a size of 0.0).
Obviously, you can configure sectionShouldBeHidden to work however you need; hiding #1 & #3 are just arbitrary examples.
Swift v5
private func sectionShouldBeHidden(_ section: Int) -> Bool {
switch section {
case 1, 3: return true
default: return false
}
}
override func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
if sectionShouldBeHidden(section) {
return nil // Show nothing for the header of hidden sections
} else {
return super.tableView(tableView, titleForHeaderInSection: section) // Use the default header for other sections
}
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if sectionShouldBeHidden(section) {
return 0 // Don't show any rows for hidden sections
} else {
return super.tableView(tableView, numberOfRowsInSection: section) // Use the default number of rows for other sections
}
}
Update: Unfortunately, the above is only enough if the style of the table view is Plain. When it's Grouped, there's also additional space added between each section, which needs taking care of too.
This extra space is the section's footer, so can be handled like so:
override public func tableView(_ tableView: UITableView, heightForFooterInSection section: Int) -> CGFloat {
if sectionShouldBeHidden(section) {
return CGFloat.leastNormalMagnitude // Use the smallest possible value for hidden sections
} else {
return super.tableView(tableView, heightForFooterInSection: section) // Use the default footer height for other sections
}
}
I tried all the solutions here with no success. At the end, adding these delegate methods this one worked:
Swift 5:
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return section == 4 ? 0 : return super.tableView(tableView, numberOfRowsInSection: section)
}
override func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
return section == 4 ? 0.1 : super.tableView(tableView, heightForHeaderInSection: section)
}
override func tableView(_ tableView: UITableView, heightForFooterInSection section: Int) -> CGFloat {
return section == 4 ? 0.1 super.tableView(tableView, heightForFooterInSection: section)
}
Note that you need to return 0.1 in height, returning 0 won't do it.
0.0 did not work for me. I had to do this in order to make it work.
override func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
switch section {
case 0:
return 0.01
default:
return UITableViewAutomaticDimension
}
}
For group UITableView with static cells only this solution works:
self.tableView.sectionHeaderHeight = 0;
self.tableView.sectionFooterHeight = 0;
override func tableView(_ tableView: UITableView, heightForFooterInSection section: Int) -> CGFloat {
let count = self.tableView(tableView, numberOfRowsInSection: section)
if count == 0 {
return CGFloat(Double.leastNormalMagnitude)
}
return 44.0
}
For anyone wanting to hide sections because they are using a static grouped tableView with a dynamic number of sections, the solution below may be of help. In my case, each section with data to display needed to have a custom header. Any section that did not have data, needed to be hidden fully.
The answer above was of great help in my scenario. However, for those who don't always know which section(s) will need to be hidden here is a solution for you extending on the above.
In my scenario, I have up to 12 entries in an array that I want to show in up to 12 sections (amongst other sections in a grouped tableView). If there are less than 12 entries to display, I want to hide the unnecessary sections by giving them 0 height and 0 rows. I also wanted to hide the headerView.
To do this, I did the following:
Set up your tableView as per the excellent answer #sasquatch gave
above.
In the numberOfRowsInSection(section: Int) and tableView(_
tableView: UITableView, heightForHeaderInSection section: Int) functions, check whether the rows/height should be 0.
In my case, I was using sections 1 - 12 for my dynamic data so I used code as below:
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
//For section 0 and 13, just 1 row is ok
if section == 0 || section == 13 {
return 1
}
//For sections 1 - 12, determine if we have data to populate it, or if we should hide it
if section <= dynamicDataToDisplay.count {
return 2
}
//If it's section 1 - 12, but we don't have a corresponding data entry in dynamicDataToDisplay, then just return 0 rows
return 0
}
The code for the heightForHeader function is similar in logic:
override func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
switch section {
case 0:
return 45.0
case 13:
return UITableViewAutomaticDimension
default:
if dynamicDataToDisplay.count >= section {
return 25.0
} else {
return 0.0
}
} //end switch
}
Even after setting up these functions, I found that I was still getting headers appearing for the sections I wanted to hide. I guess I thought that viewForHeaderInSection would not be called if the numberOfRows was 0 and heightOfHeader was also 0, but it was still being called.
Adding the following helped ensure that the header wasn't unnecessarily created:
override func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
//set up header for dynamic data sections
if 1 ... 12 ~= section {
if tableView.numberOfRows(inSection: section) == 0 {
return nil
}
//Continue with the header set up for valid sections with rows to display data
......
}
}
This solution might help anyone who is still getting a header being created despite its height and rows being set to 0.