If you have the button created on the storyboard. You have to make an
-(IBAction)clickButton...
in the .h and .m code files. You can easily connect the code to the button by dragging the line from the dot (in front of the code name) to the button.
If you have created the Button fully in code. You have to specify which code to be executed on click.
[self.buttonName addTarget:self action:@selector(clickButton:) forControlEvents:UIControlEventTouchUpInside];