Do Method

I am new to iPhone developing, so I apologize if I am using incorrect terminology here, but here goes: I need one method (IBAction) to trigger another. I want to make an action sheet, and show an alert when a button on the sheet is pressed. I have already done it, but for the sake of learning, I want to make another action to show the alert, and the first action trigger that action. something like this:

Code:

- (IBAction)trigger{
    doMethod @"showAlert"
}

So I want it to do something like that. If anyone knows how to do this, please respond. Thanks