I currently have a TableView in my project, which is set up to turn a cell green when it is pressed, and back to clear if it is pressed a second time. However, if I scroll down to the bottom of the table view, and scroll back up, all my cells have been reset to their default clear colour.
I'm not sure how to go about fixing this issue, as anything I can find referring to it is in Objective-C rather than Swift. Any help and advice as to how to go about this would be great, thanks.
Everytime a UITableViewCell goes out of the screen, any function that you've written in the tableViewController/ViewController runs again.
for example in cellForRowAtIndexPath if you have a cell.setUpCell() or something similar, it will rerun and reset your values to the original values.
if you have a
var name = testName in your MainVC
and you update something in your cell, you should change the name in your mainVc too.
Every time you scroll or call tableView.reloadData() UITableView cells will reload. So, every time you select UITableViewCell, add selected index (indexPath.row) to an array(ex: selectedIndexArray) in your didSelectRowAt indexPath: delegate. If the cell you selected is already selected one, then remove the cell from selectedIndexArray.
And in your cellForRowAt indexPath: manage the cells using selectedIndexArray.
var selectedIndexArray:[Int] = [] //to save selected tableViewCells
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let isSelected = false
for each in selectedIndexArray
{
if each == indexPath.row
{
isSelected = true
}
}
if isSelected == true
{
//set selected cell color
}
else
{
//set default cell color
}
}
You need to write the logic of adding and removing cell indexes in your didSelectRowAt indexPath:.
Related
I am working on xamarin.ios. I have a UITableView control at my view. I select a row in it and then move to next screen. If I come back to UITableView screen again the selected row doesn't highlight. It highlight for a second and then deselect automatically. How it can be managed if I come back to the tableview, the selected row should be highlighted.
Hard to say without seeing any code, but looks like the tableview is being reloaded in viewDidAppear. You may want to store the selected row index in NSUserDefaults or somewhere else to persist the selection between view loads/appearances.
Make sure you are setting it selected after the tableview reloads as well, using an appropriate delegate method. Again, without any code to look at, it's hard to see where - and which order - you're doing this, but an example (Swift):
override func tableView(tableView: UITableView, willDisplayCell cell: UITableViewCell, forRowAtIndexPath indexPath: NSIndexPath) {
if indexPath.row == tableView.numberOfRowsInSection(0) - 1 {
cell.selected = true
}
}
Alternatively, you could set the selected property in your datasource directly, and then you could do:
override func tableView(tableView: UITableView, willDisplayCell cell: UITableViewCell, forRowAtIndexPath indexPath: NSIndexPath) {
datasource[indexPath.row].selected == true {
cell.selected = true
}
}
If you do it this way, then the selected row will always be set correctly every time the tableview is loaded.
(Full disclosure, I'm not a Xamarin dev, so I'm not sure how those translate from Swift/Obj-C to Xamarin)
I am having a little trouble with buttons on a tableview.
I have a tableViewCell that I customised with 3 buttons. I set the buttons to hidden in interface builder and when the table loads the buttons are hidden as expected.
I then set the hidden property of the tableview to false when didSelectRow is called and hidden.true when didDeselectRow is called. This works fine as well. The problem is the buttons that are set to visible in the didSelectRow are also visible every seven cells down. they keep repeating themselves.
Below is the code that shows the buttons
func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
let cell = tableView.cellForRowAtIndexPath(indexPath) as! ContactsViewCell
print("Table selected")
cell.insertEmailButton.hidden = false
cell.insertPhoneButton.hidden = false
cell.insertAllButton.hidden = false
cell.contactTextLabel.alpha = 0.2
cell.contactDetailTextLabel.alpha = 0.2
}
And this hides them when the tableViewCell is deselected
func tableView(tableView: UITableView, didDeselectRowAtIndexPath indexPath: NSIndexPath) {
let cell = tableView.cellForRowAtIndexPath(indexPath) as! ContactsViewCell
cell.insertEmailButton.hidden = true
cell.insertPhoneButton.hidden = true
cell.insertAllButton.hidden = true
cell.contactTextLabel.alpha = 1.0
cell.contactDetailTextLabel.alpha = 1.0
}
I did some research and I learnt it might be the row with the buttons.hidden set to false are being reused by the tableview. But I understand from documentation that the cell being reused is from cellForRowAtIndexPath and not the cell at didSelectRow which is where I am setting the button.hidden to false.
I also tried using the cell.isSelected property in an if else statement in the cellForRowAtIndexPath to hide and show the buttons but this does not show the buttons at all.
Thanks in advance for your help
The tableview reuses the view of the cell when the table is scrolled, to save memory. So, for example, when you set the button to visible (inside didSelectRow) and then scroll down the table, the tableview will take the cells that go out of the visible screen at the top and will reuse them at the bottom, to save the overhead of creating new cells, improving performance.
That is why, your previous properties on the cells are repeating.
To get the desired hidden button on scrolled cells, I recommend setting button.hidden to true/false in
tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell
This will set the button to hidden whenever a new row is scrolled into the visible view area.
Hope this helps.
I solved the recurring buttons by hiding them when I check if the cell is deselected in cellForRowAtIndexPath. This also means any cell I select will lose its selected status and buttons will disappear when it leaves the view.
I can live with that.
if cell.selected == false{
cell.emailButton.hidden = true
cell.phoneButton.hidden = true
cell.allButton.hidden = true
}
UITableView reuses its cell to improve performance. So, you can not do the way you are trying. What we have to do is, like other tableview cell info e.g. title, description, thumb image etc we also need to save the state for buttons in the array. When you want to hide a button for the cell take object at index from the array and change the button state for the button and reload that table view cell. Still if you face problem or feel difficult to understand, please feel free to ask.
I have a tableview which is inside the a tableview cell.
After click the "JAVA" inside "test1", I click the "About" Row which don't have the tableview inside:
But you can see that, the "About" and "JAVA" have the background colour at the same time. This is the automatic feature of tableview in iOS, I don't know how to code to prevent this happen. What I want is that when I click the "Java" inside "test1", the background color of "About" would disappear.
You are going to need to keep track of which cell was selected if you only want one cell selected at a time from both table views.
The best way to do that is to create a delegate for the nested tableview. So when that cell is selected it can call back to the parent tableview and let it know to unselect anything that was selected. The main class will need to keep track of the index that was selected as if another one is chosen then it can reach into the cell with selected cell and deselect that.
A little tricky, are you sure you can't get the same results from just using one tableview and multiple sections?
Use this code it helps you
override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
var selectedCell:UITableViewCell = tableView.cellForRowAtIndexPath(indexPath)!
selectedCell.contentView.backgroundColor = UIColor.greyColor()
}
To deselect the selected row use this code
override func tableView(tableView: UITableView, didDeselectRowAtIndexPath indexPath: NSIndexPath) {
var cellToDeSelect:UITableViewCell = tableView.cellForRowAtIndexPath(indexPath)!
cellToDeSelect.contentView.backgroundColor = colorForCellUnselected
}
I want to change the image in a custom UITableViewCell, depending on whether it is selected or not.
So, when user selects a row, the image in two rows has to be changed (both the current selected and the one to be selected).
Calling reloadData, or reloadRowsAtIndexPaths from didSelectRowAtIndexPath doesn't work because it deselects the current selected row, which I don't want to happen.
Calling reloadData from willDeselectRowAtIndexPath and willSelectRowAtIndexPath also causes the same problem.
Anyone know a solution for this?
Did you try just programmatically selecting the row in cellForRowAtIndexPath based on a stored property indicating the selected row?
I would an approach where you still use reloadData, or reloadRowsAtIndexPaths from didSelectRowAtIndexPath but first save the selected row in a property so that you can manually set it as selected when the cell is redrawn.
For example:
var selectedRow:NSIndexPath? = nil
override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
selectedRow = indexPath
tableView.reloadData() // or reload a specific row
}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("TableViewCellReuseIdentifier")
if (indexPath == selectedRow) {
cell!.selected = true
} else {
cell!.selected = false
}
}
I have a UITableView with the subtitles hidden but set up where when someone selects a cell it shows that cell's subtitle. This works fine except that after tapping any cell to reveal its subtitle if you scroll down you will find that every 12 cells have their subtitle unhidden (as well as the one it was supposed to reveal). Here is the code I'm using in didSelectRowAtIndexPath:
override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
for cell in tableView.visibleCells() {
cell.detailTextLabel??.hidden = true
}
var cell = tableView.cellForRowAtIndexPath(indexPath)
cell?.detailTextLabel?.hidden = false
}
I'm sure this is related to ".visibleCells()" since every 12 cells is about the height of my visible table on my iPhone 6 Plus. When I run it on a 4s in the simulator it's about every 8 cells. But I'm not sure how else to do it besides 'visibleCells'? But it's strange because it's the whole table - all the way down, every 12 cells is showing its subtitle...
thanks for any help
UITableView reuses its cells. So the cell for row a row you clicked on (unhidden the subtitle) may be used for row another row.
The solution is to define prepareForReuse() method in the UITableViewCell subclass (or make the subclass if you do not have one) and hide the subtitle again there.
Add that dataSource's method to your controller. Should work fine.
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) {
var identifier = "cellIdentifier"
var cell = tableView. dequeueReusableCellWithIdentifier(identifier, forIndexPath: indexPath)
cell.detailTextLabel?.hidden = true
return cell
}