Passing custom data in [UIButton addTarget]

How 开发者_开发知识库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

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.

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.

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.

E.g.

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.