I can convert any website to IOS app quickly.
For App conversion your website should have following features
1) Responsive Design
2) Should rendered perfectly in all screen size
Your website will looks same in app as you can see in mobile browser
If you site is not responsive then you check this gig
For website to Android please check below service
IOS: (Website to app)
Note: Add extra native features like Push Notification, Tabs, Bottom menu. It will help you for approving your app in the App Store.