大道至簡，直接上程式碼

-(void)setButtonContentCenter:(UIButton *) btn

{

    CGSize imgViewSize,titleSize,btnSize;

    UIEdgeInsets imageViewEdge,titleEdge;

    CGFloat heightSpace = 10.0f;

    //設定按鈕內邊距

    imgViewSize = btn.imageView.bounds.size;

    titleSize = btn.titleLabel.bounds.size;

    btnSize = btn.bounds

    imageViewEdge = UIEdgeInsetsMake(heightSpace,0.0, btnSize.height -imgViewSize.height - heightSpace, - titleSize.width);

    [btn setImageEdgeInsets:imageViewEdge];

    titleEdge = UIEdgeInsetsMake(imgViewSize.height +heightSpace, - imgViewSize.width, 0.0, 0.0);

    [btn setTitleEdgeInsets:titleEdge];

}

重點參考：

iOS UIButton 設定圖片文字垂直排列

iOS - UIButton(UIEdgeInsets)／設定button上的文字和圖片上下垂直居中對齊