botton.imageEdgeInsets = UIEdgeInsetsMake(- (botton.frame.size.height - botton.imageView.frame.size.height)/2, 0, (botton.frame.size.height - botton.imageView.frame.size.height)/2, 0); botton.titleEdgeInsets = UIEdgeInsetsMake(0, - (botton.imageView.frame.size.width/2 + botton.titleLabel.frame.size.width/2), 0, (botton.imageView.frame.size.width/2 + botton.titleLabel.frame.size.width/2));
核心代码：
UIEdgeInsetsMake(top, left, bottom, right);
由于Y轴通过top、bottom控制，在设置偏移量的时候要同时修改，如只修改一边，则偏移量倍数要x2（X轴同解）
原文：http://www.cnblogs.com/ly1992/p/4950594.html