Pokémon GO Redeem might give you problems if you're on iOS. Android users can redeem codes directly in game, but Apple users don't get the option. How do you redeem codes in Pokémon GO?
Pokémon GO Redeem: How to Redeem Codes
If you're trying to get in on the latest The North Face x Gucci collaboration in Pokémon GO, you'll want to know how to redeem codes for the in-game cosmetics. Android players can redeem codes in-game, but Apple users have to get around some App Store regulations.
To redeem Pokémon GO codes on iOS, you have to use the Niantic Rewards website. Log in with your Pokémon GO credentials, and then you can punch in your desired code. It should then appear in your game. Android users can also use the Niantic Rewards website, but it's easier to go through the game's menu.
As for how to get codes, Niantic will periodically release codes in collaboration with other brands, such as Verizon or Gucci. They will also send codes to absent players to entice them to return and often have codes during live events. There aren't many verified codes floating around, but it doesn't hurt to try all of them as there's no penalty for wrong codes.