设置contentHorizontalAlignment
button.contentHorizontalAlignment = UIControlContentHorizontalAlignmentLeft;
button.titleEdgeInsets = UIEdgeInsetsMake(0, 10, 0, 0);
button.contentHorizontalAlignment = UIControlContentHorizontalAlignmentLeft;
button.titleEdgeInsets = UIEdgeInsetsMake(0, 10, 0, 0);