How to make UIButton's text alignment center? Using IB

This will make exactly what you were expecting:

Objective-C:

 [myButton.titleLabel setTextAlignment:UITextAlignmentCenter];

For iOS 6 or higher it's

 [myButton.titleLabel setTextAlignment: NSTextAlignmentCenter];

as explained in tyler53's answer

Swift:

myButton.titleLabel?.textAlignment = NSTextAlignment.Center

Swift 4.x and above

myButton.titleLabel?.textAlignment = .center

Use the line:

myButton.contentHorizontalAlignment = UIControlContentHorizontalAlignmentCenter;

This should center the content (horizontally).

And if you want to set the text inside the label to the center as well, use:

[labelOne setTextAlignment:UITextAlignmentCenter];

If you want to use IB, I've got a small example here which is linked in XCode 4 but should provide enough detail (also mind, on top of that properties screen it shows the property tab. You can find the same tabs in XCode 3.x):