Some serious usability issues with anti-patterns. - Why navigation bar on bottom of screen? - Sometimes close is in left, sometimes on bottom. Pick one. - Overusing the blurred background pattern. Use it sparingly to provide context, or layering. - 3 dots icon is sharing? - No search for finding activities - When you tap a sport, it spawns multiple view controllers. Leads to crashing the app.
I like the consistent use of blurred backgrounds too. However on the sports scroll I'd wait until the scroll has settled to change the background image -- when you're scrolling quickly through the list it can cause the app to stutter.
Great work overall! Your app is beautiful.