Build Android and iOS apps for our event company

Our company Young Yaa [login to view URL] is a company whose main business is creating and holding event and activity. We need apps on both iOS and Android platform to enforce our influence and provide convinience for our members. The apps needs to have the following function groups: 1. Company News At back-end of the apps, admin can manage (publish, unpublish, edit, etc) company news. 2. Event List and Booking At back-end of the apps, admin can manage (publish, unpublish, edit, related coupon, etc) events. Events have a lot of types. For most of the types, we just need registed users to be able to view the event detail and book it. The ticket for events could be free or with price. So you need to integrate Paypay and Debit/Credit Card gateway to it. One of the special type of the event is the online seckilling event. It's different from other kinds of events. Once a logged user click a seckilling event in the event list, he/she should enter the online seckilling page. Here is the specification of the seckilling event: 1) Only users who logged in to our apps can view the seckilling page and take part in the activity 2) In everyday of a period of time, our app members can 'grab' an award specified by us every n (like 5, 10, 15...)minutes. For example, in one day during 17th-30th, before 21:00:00, the app event detail page only says 'Today's seckilling still has [here is a timer to count down until 21:00:00] to start'; at 21:00:00 the page shows a button 'Grab It', allowing subscribers to press it. The app back-end records the first one who press the button and pop up an alert box to him notifying him 'Congradulation, You Grab the Award First!' as well as sending our web admin a email telling us who win the award at what time, while also notifying others who pressed the button a little late by 'Sorry, you are a bit slow, please try for the next chance'. At the moment when the back-end detected the first one who presses the button, the button on the page should be replaced by a timer which shows the time to the next seckilling section at 21:05:00 like '4:33:12 to the seckilling of the next time'. After the last section finished at 21:30, the page should show 'Today's seckilling has all finished, please come back tomorrow'. 3) On our app back-end we should be able to set the start and finish date of the seckilling event ( for the future use ), the interval time of every seckilling section, the award of every section in every day ( of course before the section starts ). 3. User System User should be able to register and log in/out. Right after registration, user should be able to subscribe to different membership plan (Free, $10/y, $20/y), so you need to integrate Paypay and Debit/Credit Card gateway to it. Our Joomla website use Membershp Pro extension to manage membership and subscription. User data, membership and profile should be automatically syncronized with that on our Joomla website (using MySQL, and could be remotely connected). In the user center, user could change profile. He should also be able to see his event booking, history of the event he has taken part in. It should have a coupon management system. When user books some of the events, they could get coupon. The coupon should also be able to be set in the back-end event management system. Finally, after confirming the apps, they should be published to the Google Play and App Store as soon as possible (A milestone would be binded to this). User could download them. To sum up, you need to create app on both iOS (compatible to iPhone and iPad) and Android, as well as an uniformed back-end management for them. This is an urgent project. For simlicity you could keep the UI of Android and iOS version the same. You could use any technich you want: Java, Objectve-C or Swift, Angular JS, etc. Attachement files include a function list, some screenshots of seckilling event (Note: it's just a special type in our event list) from some Chinese apps.