Passing custom data in [UIButton addTarget]

Question

How do I add custom data while specifying a target in a UIButton ?

id data = getSomeData();
[button addTarget:self 
           action:@selector(buyButtonTapped:event:) 
 forControlEvents:UIControlEventTouchUpInside];

I want the buyButtonTapped function to look like:

(void) buyButtonTapped: (UIButton *) button event: (id) event data: (id) data

Answer 1

not possible. the action that is triggered by an UIControl can have 3 different signatures.

- (void)action
- (void)action:(id)sender
- (void)action:(id)sender forEvent:(UIEvent *)event

None of them allows you to send custom data.

---

Depending on what you want to do you can access the data in different ways.

For example if the button is in a UITableView you could use something like this:

- (IBAction)buttonPressed:(UIButton *)sender {
    CGPoint buttonOriginInTableView = [sender convertPoint:CGPointZero toView:tableView];
    NSIndexPath *indexPath = [tableView indexPathForRowAtPoint:buttonOriginInTableView];
    NSData *customData = [myDataSource customDataForIndexPath:indexPath];
    // do something
}

There is always a way to get the data without passing it to the button.

Answer 2

You cannot send extra data to the action method. There are a number of ways to associate the data with the button, although none are particularly straightforward unless the data is a single NSInteger.

• You can use the tag property to hold a single NSInteger. This may be all you need, or you could use it to look up an object in an array or dictionary.
• You can subclass UIButton to add ivars/properties to store your needed data.
• You can use [NSValue valueWithNonretainedObject:button] as a key for a dictionary.
• My personal favorite for one-offs, you can use [associative references] to associate the data object with the button.

Answer 3

You can't really do that. What you can do is put the data in a dictionary and use the button to get it later.

Eg

myDataDict = [NSDictionary dictionaryWithObjectsAndKeys:someData, button, nil];

Then later;

-(void) buttonPress:(id)sender
{
  data = [dataDict objectForKey:sender];
}

If your buttons are specified in InterfaceBuilder you can use the 'tag' property of a button to lookup the data, although you will need to convert it to an NSNumber for use with the dictionary.