支持生成二维码，扫描二维码功能,最少支持苹果ios7.0，二维码的中间还可以放置头像-Support to generate the qr code, scan qr code function, minimum support apple ios7.0, qr code still can be placed in the middle of the picture

一个可缩放可拖动的自定义ButtonView，可设置最大最小宽高。-A scalable draggable custom ButtonView, you can set the maximum and minimum width and height.