iphone development: changing the button image on tableviewcell - iphone

Question

In my app I am facing with a really weird problem. I am trying to solve it for hours but could not find what is the problem so far.
Well, I have a tableview with custom cells. and each cell I have a button. It is is like an empty box. When the button pressed, I want to change the related cell image of that button. Actually I successfully do that but somehow, some other cell's button images are also changing and I could not figure out why. Here is my code:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"cell";
CustomCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil)
{
//create new cell
cell = [[CustomCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
[cell.tickButton setTag:indexPath.row];
[cell.tickButton addTarget:self action:#selector(buttonWasPressed:)forControlEvents:UIControlEventTouchUpInside];
//cell has 2 label so I filled them with the contents of my object array that part is working with no problem
cell.leftLabel.text = [NSString stringWithFormat:#"%#", [[contacts objectAtIndex:indexPath.row]name]];
cell.rightLabel.text = [NSString stringWithFormat:#"%#", [[contacts objectAtIndex:indexPath.row]email]];
return cell;
}
in my buttonWasPressed method I simply do:
-(IBAction)buttonWasPressed:(id)sender
{
UIButton *button = (UIButton *)sender;
[button setImage:[UIImage imageNamed:#"ticck.jpeg"] forState:UIControlStateNormal];
}
As I said before it works but also changes some other buttons images and also when I scroll down and get back to the initial position I see that some button images are changed.

Answer 1

You can access that cell and can change the button image as :
-(IBAction)buttonWasPressed:(id)sender
{
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:your_row inSection:your_section];
UITableViewCell *currentCell = [table cellForRowAtIndexPath:indexPath];
UIButton *button = (UIButton *)[currentCell viewWithTag:(UIButton *)sender.tag];
[button setImage:[UIImage imageNamed:#"ticck.jpeg"] forState:UIControlStateNormal];
}
Hope it helps you.

Answer 2

You can deal with touch within CustomCell class. Just move method -(IBAction)buttonWasPressed:(id)sender within your custom class and add
tickButton addTarget:selfaction:#selector(buttonWasPressed:)forControlEvents:UIControlEventTouchUpInside in init method.

Answer 3

The problem is calling
[cell.tickButton addTarget:self action:#selector(buttonWasPressed:)forControlEvents:UIControlEventTouchUpInside];
method.
You add target everytime when your cells are reused and remove never. So your buttons have many targets and action method get called multiple times respectively. It may cause a memory leak.
Just put the addTarget method in if clause.
It will solve your one problem, which is your method get called multiple times. But when the cell is reused the button has the changed image. You need to set it back.
The best way to do that, you add a property to the contact object which are preseted in cells and set a value when the action method is fired. Then in cellForRowAtIndexPath: method you can set the image of the button by checking that property.

Answer 4

Do this
NSString *CellIdentifier = [NSString stringWithFormat:#"cell%d",indexPath.row];

Answer 5

While you set the default image to button also do this
[button setImage:[UIImage imageNamed:#"ticck.jpeg"] forState:UIControlStateSelected];
In your button action method do this:
-(IBAction)buttonWasPressed:(id)sender
{
UIButton *button = (UIButton *)sender;
if(button.selected==NO) {
[button setSelected:YES];
}
}
Hope this helps.

Answer 6

To reuse your cell, you have to make it clean after dequeueing. In this case, you should reset your image first:
[cell.tickButton setImage:nil forState:UIControlStateNormal];
Before assigning anything to your cell.

Answer 7

You must save button's tag which was pressed than try this
if(pressed[cell.tickButton.tag])
[button setImage:[UIImage imageNamed:#"ticck.jpeg"] forState:UIControlStateNormal];
else
[cell.tickButton setImage:nil forState:UIControlStateNormal];

Answer 8

I guess you are giving the default image to your button inside the CustomCell class. This problem is very common in UITableviews.
All you need to do is keep track of the cells for which the button has been pressed. Do all this inside the cellForRowAtIndexPath method.
For example:
update the code inside cellForRowAtIndexPath method
if (cell == nil)
{
//create new cell
cell = [[CustomCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
if(yourCondition==YES){
change the button image to the special image.
}
else{
keep the button image as default image.
}
return cell;
To keep track of the cells you can store the index path of the cells(whose button has been tapped) in an array. Inside cellForRowAtIndexPath check if the current indexPath is present inside your array or not