The associated project contains the bug and the ReadMe.txt file explains what the bug does. Part of the challenge is to find the error and fix it yourself. The later project files do not contain these bugs of course but there is no video explaining what the solutions are.
You can see that the background of the collectionView behind the cards is black. You may not recall the earlier setup process of configuring the cell layout in storyboard, but that was covered so that the background image can be seen through the collectionView.
Hint: Have a look at the settings for the collectionView background property.
There are 17 cards instead of 16 when you run the App. This is a sneaky bug and it is related to the getCards() method in the class CardModel in the file CardModel.swift.
Hint: Go back to Lesson 4 on the Custom Classes setup and watch closely while referring to the code with the bug in it.
When you run the App the some of the cards when flipped reveal a card that is blank. This is a sneaky bug but you should be able to figure it out by going over the code that creates the set of 8 pairs of cards since that is where the bug is. The interesting thing about this bug is that the program lets you match blank cards which makes sense when you understand the code with respect to how it is comparing the tow cards to determine if they are the same. Once you find the bug it will all make sense.
Same hint as the previous Activity.