Such a compact but neat and heavy screen is this. Can be done using Objective C and Storyboard without any interruption.
It will be better if we can use auto layout to design that screen to support 3.5 inches to 9.56 inches of all views. Looks like it's not a big project that will take so much time to complete. So rather than create different UIViews for different iPhone and iPad devices we should use auto layout.
Another thing, we should go with image URLs rather than raw images(.png, . jpeg, .jpeg etc ). If we use logo images(low size) then it's fine, but it will increase the app size whenever we use some bigger size of images(1500). So if you have total 1500 high resolution images (near about 1 mb or greater) then we need to generate URLs from each images before use. Does it mean?
1. Animated expand and collapse animation >> For this we'll use View Transitions (native animation to Apple) animation.
2. minimum iOS version: iOS 9 >> ok, we will set the minimum deployment target as iOS9.
3. iPad, iPhone x, iPhone 6 plus, 7 plus can have 6 x 7 items(42) into the collection view to show perfectly.
4. The grid items will be as a bit smaller on iPhone 4 and 5. But it's certain sure that the expanding section must be visible also in iPhone 4 and 5.
5. Tapping a section header must make that section expand/collapse>> ok
6. Yes, Scrolling will be smooth and supports full scrolling even ALL sections will be expanded though.
Please let us know your feedback. Thanks.