Programmatically created UIButton did not respond to clicks

When I tried creating a UIButton programmatically, it at first did not respond to clicks. This was even after I had added a callback for the button, as below:

[exitButton addTarget:self action:@selector(exitButtonPressed) forControlEvents:UIControlEventTouchUpInside];

 

After some troubleshooting, I found the source of the problem. It was because the size of the button was not defined. Once the size was defined, the button became responsive to clicks.

CGRect exitButtonFrame = exitButton.frame;

exitButtonFrame.size.width = 32;

exitButtonFrame.size.height = 32;

exitButtonView.frame = exitButtonFrame;