Oppo Sonica app no longer available in App Store for iPad

I love my Oppo Sonica Wi-Fi Speaker. However its app is no longer available in the App Store which means I cannot control my Sonica Speaker from my new iPad. Is there any workaround to load the Oppo Sonica App to iPad? Is there any hope of Apple returning the Oppo Sonica App to the App Store?

[Re-Titled by Moderator]

Original Title: Oppo Sonica App