Swift
//Align contents to the left of the frame
button.contentHorizontalAlignment = .left
//Align contents to the right of the frame
button.contentHorizontalAlignment = .right
//Align contents to the center of the frame
button.contentHorizontalAlignment = .center
//Make contents fill the frame
button.contentHorizontalAlignment = .fill
Objective C
//Align contents to the left
button.contentHorizontalAlignment = UIControlContentHorizontalAlignmentLeft;
//Align contents to the right
button.contentHorizontalAlignment = UIControlContentHorizontalAlignmentRight;
//Align contents to the center
button.contentHorizontalAlignment = UIControlContentHorizontalAlignmentCenter;
//Align contents to fill the frame
button.contentHorizontalAlignment = UIControlContentHorizontalAlignmentFill;