Game logic implemented already.

The only required thing is custom back button icon.
Adding content controller

Main gui and text field results handling. There nothing happens with those results and there is bug with not resizing fields when keyboard appears.
Help view controller.

It shows help, but there is no help. It'd be better to use resource strings for help content.
Statistics counts

User can count number of guessed cards and total number of cards, and this statistics is saved between application launches.
Login screen started, card view controllers reused

Login screen was slightly modified, but it still doesn't work properle.
Card view controllers are created only once, and then they are reused with changing its data source card. Their views are added just once, and then only thir visibility changes.