Detecting which button pressed

Question

I want to be able to detect which button is pressed. I wonder if there is some UIButton class method which can will be called automatically when a button is pressed, which allows me to find out the text or tag of the button pressed and pass that on to a variable? Or some objective-c event method that does the same?

I know this topic has been posted here before. The common response appears to be that this would be the solution:

In .h file

- (IBAction)buttonClicked:(UIButton *)sender;

In .m file

- (IBAction)buttonPressed:(UIButton *)sender{
// Do something her to display which button pressed
}

I have also seen other examples with names such as buttonPressed, onButtonTao etc.

So I assume that this method must be called from each button. However, this does not work, xcode complains when I try to assign the same method to more than one button.

The following example, posted here at Stack, uses the same action, but programatically:

for( int i = 0; i < 5; i++ ) {
  UIButton* aButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
  [aButton setTag:i];
  [aButton addTarget:self action:@selector(buttonClicked:) forControlEvents:UIControlEventTouchUpInside];
  [aView addSubview:aButton];
}

// then ...

- (void)buttonClicked:(UIButton*)button
{
  NSLog(@"Button %ld clicked.", (long int)[button tag]);
}

So, what am I missing here, why does xcode not accept the same method for multiple buttons? And is there some other way to detect which button is pressed without connecting a specific action to each and every button?

Answer 1

You can connect more than one button to the same action method in Xcode. After creating and connecting the first action, control-drag the remaining buttons to the existing action in the .h file:

Then you can assign different tags to the buttons in the Attributes Inspector, and check [sender tag] in the action method.

If you create a new action with the same name, Xcode creates another method with the same name, which will cause compiler errors due to "duplicate declarations".

Answer 2

It looks like you are trying to Copy-Paste this Sample into your Code and it's not working, right ? You should provide Frame to the Buttons.

Here is the Working Code :

for( int i = 0; i < 5; i++ ) 
{
    UIButton* aButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    aButton.frame = CGRectMake(10 + i*50,10,50,50);
    [aButton setTag:i];
    [aButton addTarget:self action:@selector(buttonClicked:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:aButton];
}

Here, frame should not be static otherwise the Buttons will be overlapped.