Continue working on last weeks hw to incorporate more advanced/custom UI (UITableViewCell, MKMapView, etc).
Continue working on the Instagram™ clone. Figure out how to get more accurate colors/fonts. Add a search bar that allows you to search by tag. Use the official Instagram™ app as a reference.
Bonus:
Feeling adventerous? Check out UICollectionViewController!
Check out https://www.cocoacontrols.com/controls. This website provides examples of custom UI for iOS as well as links to github projects or directly to cocoapods. Pick 1 or 2 interesting UI concepts and make them work inside of your own application.
Take a look a [UIView animationWithDuration...] or CAAnimation. Build a little app that demos different types of animation.
Bonus:
Incorporate Facebook's Pop animation framework (https://github.com/facebook/pop)