iOS developer to upgrade an app from Swift 2.3 to 3

Job description

The client is looking for an iOS developer to update the app of a customer from Swift 2.3 to Swift 3. Additionally, one new feature should be developed, but the Swift upgrade is the main goal.
The app that should be upgraded is this one: https://itunes.apple.com/us/app/europa-park/id378319816

Must have skills
Swift

Start date
Earliest: asap

Length
1-3 months

Engagement
Fulltime

Remote
Not possible