Detecting which UIButton was pressed in a UITableV

Question

I have a UITableView with 5 UITableViewCells. Each cell contains a UIButton which is set up as follows:

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
     NSString *identifier = @"identifier";
     UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:identifier];
     if (cell == nil) {
         cell = [[UITableView alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:identifier];
         [cell autorelelase];

         UIButton *button = [[UIButton alloc] initWithFrame:CGRectMake(10, 5, 40, 20)];
         [button addTarget:self action:@selector(buttonPressedAction:) forControlEvents:UIControlEventTouchUpInside];
         [button setTag:1];
         [cell.contentView addSubview:button];

         [button release];
     }

     UIButton *button = (UIButton *)[cell viewWithTag:1];
     [button setTitle:@"Edit" forState:UIControlStateNormal];

     return cell;
}

My question is this: in the buttonPressedAction: method, how do I know which button has been pressed. I've considered using tags but I'm not sure this is the best route. I'd like to be able to somehow tag the indexPath onto the control.

- (void)buttonPressedAction:(id)sender
{
    UIButton *button = (UIButton *)sender;
    // how do I know which button sent this message?
    // processing button press for this row requires an indexPath. 
}

What's the standard way of doing this?

Edit:

I've kinda solved it by doing the following. I would still like to have an opinion whether this is the standard way of doing it or is there a better way?

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
     NSString *identifier = @"identifier";
     UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:identifier];
     if (cell == nil) {
         cell = [[UITableView alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:identifier];
         [cell autorelelase];

         UIButton *button = [[UIButton alloc] initWithFrame:CGRectMake(10, 5, 40, 20)];
         [button addTarget:self action:@selector(buttonPressedAction:) forControlEvents:UIControlEventTouchUpInside];
         [cell.contentView addSubview:button];

         [button release];
     }

     UIButton *button = (UIButton *)[cell.contentView.subviews objectAtIndex:0];
     [button setTag:indexPath.row];
     [button setTitle:@"Edit" forState:UIControlStateNormal];

     return cell;
}

- (void)buttonPressedAction:(id)sender
{
    UIButton *button = (UIButton *)sender;
    int row = button.tag;
}

What's important to note is that I can't set the tag in the creation of the cell since the cell might be dequeued instead. It feels very dirty. There must be a better way.

Answer 1

A slight variation on Cocoanuts answer (that helped me solve this) when the button was in the footer of a table (which prevents you from finding the 'clicked cell':

-(IBAction) buttonAction:(id)sender;
{
    id parent1 = [sender superview];   // UiTableViewCellContentView
    id parent2 = [parent1 superview];  // custom cell containing the content view
    id parent3 = [parent2 superview];  // UITableView containing the cell
    id parent4 = [parent3 superview];  // UIView containing the table

    UIView *myContentView = (UIView *)parent1;
    UITableViewCell *myTableCell = (UITableViewCell *)parent2;
    UITableView *myTable = (UITableView *)parent3;
    UIView *mainView = (UIView *)parent4;

    CGRect footerViewRect = myTableCell.frame;
    CGRect rect3 = [myTable convertRect:footerViewRect toView:mainView];    

    [cc doSomethingOnScreenAtY:rect3.origin.y];
}

Answer 2

SWIFT 2 UPDATE

Here's how to find out which button was tapped + send data to another ViewController from that button's indexPath.row as I'm assuming that's the point for most!

@IBAction func yourButton(sender: AnyObject) {


     var position: CGPoint = sender.convertPoint(CGPointZero, toView: self.tableView)
        let indexPath = self.tableView.indexPathForRowAtPoint(position)
        let cell: UITableViewCell = tableView.cellForRowAtIndexPath(indexPath!)! as
        UITableViewCell
        print(indexPath?.row)
        print("Tap tap tap tap")

    }

For those who are using a ViewController class and added a tableView, I'm using a ViewController instead of a TableViewController so I manually added the tableView in order to access it.

Here is the code for passing data to another VC when tapping that button and passing the cell's indexPath.row

@IBAction func moreInfo(sender: AnyObject) {

    let yourOtherVC = self.storyboard!.instantiateViewControllerWithIdentifier("yourOtherVC") as! YourOtherVCVIewController



    var position: CGPoint = sender.convertPoint(CGPointZero, toView: self.tableView)
    let indexPath = self.tableView.indexPathForRowAtPoint(position)
    let cell: UITableViewCell = tableView.cellForRowAtIndexPath(indexPath!)! as
    UITableViewCell
    print(indexPath?.row)
    print("Button tapped")


    yourOtherVC.yourVarName = [self.otherVCVariable[indexPath!.row]]

    self.presentViewController(yourNewVC, animated: true, completion: nil)

}

Answer 3

This problem has two parts:

1) Getting the index path of UITableViewCell which contains pressed UIButton

There are some suggestions like:

• Updating UIButton's tag in cellForRowAtIndexPath: method using index path's row value. This is not an good solution as it requires updating tag continuously and it does not work with table views with more than one section.

• Adding an NSIndexPath property to custom cell and updating it instead of UIButton's tag in cellForRowAtIndexPath: method. This solves multiple section problem but still not good as it requires updating always.

• Keeping a weak refence to parent UITableView in the custom cell while creating it and using indexPathForCell: method to get the index path. Seems a little bit better, no need to update anything in cellForRowAtIndexPath: method, but still requires setting a weak reference when the custom cell is created.

• Using cell's superView property to get a reference to parent UITableView. No need to add any properties to the custom cell, and no need to set/update anything on creation/later. But cell's superView depends on iOS implementation details. So it can not be used directly.

But this can be achieved using a simple loop, as we are sure the cell in question has to be in a UITableView:

UIView* view = self;
while (view && ![view isKindOfClass:UITableView.class])
    view = view.superview;
UITableView* parentTableView = (UITableView*)view;

So, these suggestions can be combined into a simple and safe custom cell method for getting the index path:

- (NSIndexPath *)indexPath
{
    UIView* view = self;

    while (view && ![view isKindOfClass:UITableView.class])
        view = view.superview;

    return [(UITableView*)view indexPathForCell:self];
}

From now on, this method can be used to detect which UIButton is pressed.

2) Informing other parties about button press event

After internally knowing which UIButton is pressed in which custom cell with exact index path, this information needs to be sent to other parties (most probably the view controller handling the UITableView). So, this button click event can be handled in a similar abstraction and logic level to didSelectRowAtIndexPath: method of UITableView delegate.

Two approaches can be used for this:

a) Delegation: custom cell can have a delegate property and can define a protocol. When button is pressed it just performs it's delegate methods on it's delegate property. But this delegate property needs to be set for each custom cell when they are created. As an alternative, custom cell can choose to perform its delegate methods on it's parent table view's delegate too.

b) Notification Center: custom cells can define a custom notification name and post this notification with the index path and parent table view information provided in userInfo object. No need to set anything for each cell, just adding an observer for the custom cell's notification is enough.

Answer 4

It works for me aswell, Thanks @Cocoanut

I found the method of using the superview's superview to obtain a reference to the cell's indexPath worked perfectly. Thanks to iphonedevbook.com (macnsmith) for the tip link text

-(void)buttonPressed:(id)sender {
 UITableViewCell *clickedCell = (UITableViewCell *)[[sender superview] superview];
 NSIndexPath *clickedButtonPath = [self.tableView indexPathForCell:clickedCell];
...

}

Answer 5

It's simple; make a custom cell and take a outlet of button

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
    {
         NSString *identifier = @"identifier";
        customCell *cell = [tableView dequeueReusableCellWithIdentifier:identifier];

    cell.yourButton.tag = indexPath.Row;

- (void)buttonPressedAction:(id)sender

change id in above method to (UIButton *)

You can get the value that which button is being tapped by doing sender.tag.

Answer 6

I always use tags.

You need to subclass the UITableviewCell and handle the button press from there.