If you have code such as this, then p will be "2.99":
let price = 2.99
let p = String(format: "%.2f", price)
However, if you have code like this:
let priceNS: NSDecimalNumber = 2.99
let p2 = String(format: "%.2f", priceNS)
Then p2 is "0.00".
How can you format an NSDecimalNumber into a string like this? (NSDecimalNumber is how the price in an SKProduct is stored)