使用UIActivityViewController分享时，限制分享

 let shareImage = UIImage.init(named: "qrcode")

        let items = [shareImage!]

        let activeVC = UIActivityViewController.init(activityItems: items,applicationActivities: [UIActivity.init()])

        //设置可以分享的种类

        activeVC.excludedActivityTypes = [UIActivityType.postToFacebook, UIActivityType.postToWeibo, .airDrop, .addToReadingList, .assignToContact, .mail, .message, .postToTencentWeibo]

        present(activeVC, animated: true, completion: nil)