Automatically adding UI elements to the UIStackView while UITable Scrolling - ios

Question

In my app have an UITable.In the table cell i have added UIStackView to populate while loading the table cell.
It was working fine till scroll down the table, The stack view get added more elements when I scrolling up and down. (elements means UIButtons, I will replace them with UIlabel in future)
I don't have any idea to solve this problem. Thank you..
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier];
UIStackView *stkItems=(UIStackView *)[cell viewWithTag:8];
for(int i=0;i<5;i++) {
UIButton *btn=[UIButton buttonWithType:UIButtonTypeSystem];
[btn setTitle:#"test btn" forState:UIControlStateNormal];
[stkItems addArrangedSubview:btn];
}
}

Answer 1

A table view reuses cells when they go off the screen. That's why you're sending a message named dequeueReusableCellWithIdentifier:. You never take buttons out of the stack view. Every time the cell is reused, you add five more buttons to the buttons that are already in the stack view.

Answer 2

I had a similar issue, adding arrangedSubviews in a tableview cell.
The trick here is, in the prepareForResue of your cell, remove each of your stackView's subviews from their superview with removeFromSuperview, AND, call the removeArrangedSubview.
Is should look like this :
for view in self.views {
radioView.removeFromSuperview()
}
self.views.removeAll()
for arrangedSubview in self.stackView.arrangedSubviews {
self.stackView.removeArrangedSubview(arrangedSubview)
}
As the Apple documentation says :
[The removeArrangedSubview] method does not remove the provided view
from the stack’s subviews array; therefore, the view is still
displayed as part of the view hierarchy.
Hope it will help someone ;)

Answer 3

From that code it seems that every time your app needs to draw a cell it will add buttons to the UIStackView, so when a cell is reused (by the dequeueReusableCellWithIdentifier) it still contains the buttons, but your code keeps adding more every time. Maybe you should check if the UIStackView has enough buttons or clear all buttons and add what you need.
Hope this helps

Answer 4

i think i solved it. But I don't know is it up to standard.
this is the updated.
i have initialized and declare it to 0 on up.
#implementation HistoryViewController
int data=0;
and change cellForRowAtIndexPath like this so it will not update same stackview again
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
NSLog(#"%ld",indexPath.row);
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier];
if(data <=indexPath.row)
{
data=(int)indexPath.row;
UIStackView *stkItems=(UIStackView *)[cell viewWithTag:8];
[stkItems.subviews makeObjectsPerformSelector: #selector(removeFromSuperview)];
for(int i=0;i<5;i++) {
UIButton *btn=[UIButton buttonWithType:UIButtonTypeSystem];
[btn setTitle:#"test btn" forState:UIControlStateNormal];
[stkItems addArrangedSubview:btn];
}
}
return cell;
}

Answer 5

Since the cell is reusing the UIStackView you have to remove any subviews before you add new ones. To do this just call the following code before you loop through and add the arranged subviews to your UIStackView:
Swift 3
for view in stackView.arrangedSubviews {
view.removeFromSuperview()
}
Objective-C
for (UIView *view in stackView.arrangedSubviews) {
[view removeFromSuperview];
}
*Note: If you call [stackView removeArrangedSubview:view] according to Apple's comments it doesn't actually remove it completely from the receiver. See quote below:
- (void)removeArrangedSubview:(UIView *)view
"Removes a subview from the list of arranged subviews without removing it as
a subview of the receiver.
To remove the view as a subview, send it -removeFromSuperview as usual;
the relevant UIStackView will remove it from its arrangedSubviews list
automatically."