UIButton图片文字上下布局

//使图片和文字水平居中显示
    btn.contentHorizontalAlignment = UIControlContentHorizontalAlignmentCenter;

    //文字距离上边框的距离增加imageView的高度，距离左边框减少imageView的宽度，距离下边框和右边框距离不变
    [btn setTitleEdgeInsets:UIEdgeInsetsMake(btn.imageView.frame.size.height + 5 ,-btn.imageView.frame.size.width, 0.0,0.0)];

    //图片距离右边框距离减少图片的宽度，其它不边
    [btn setImageEdgeInsets:UIEdgeInsetsMake(-15, 0.0,0.0, -btn.titleLabel.bounds.size.width)];