I used this book to learn Swift myself: https://www.amazon.com/Swift-Programming-Ranch-Guide-Guides/dp/0134398017/ref=zg_bs_11006483011_9?_encoding=UTF8&psc=1&refRID=QB9A6SG45W3B7F59JXWQ
I thought it was a good guide. In terms of textbooks, there are a lot out there. Some are catered more towards advanced programmers looking for a primer, others are geared towards teaching good programming concepts to beginners who've never programmed before.
How much programming do you already know? Is Swift going to be your first language? These are important questions to answer for understanding what textbook/course/resource you need to look for to learn more.
On the game side, there are also several game engines that support integration into iOS as well, such as Unreal and Unity. I haven't used Unreal myself, but with Unity you can create an iOS project from the Unity editor itself, which can then be deployed onto an iOS device.
I would recommend also learning about some game engines as well. Maybe not right this minute, but once you are comfortable with Swift and iOS basics, I would look into game engines then. If you are going to look into a game engine, you will probably need to learn another programming language (though that isn't necessarily the case), such as C# or C++, for Unity and Unreal respectively. There are some great guides for both languages. Really there are so many guides for those languages, and again, it's important to pick one that looks right for you and using it (i.e. is it for a beginner or an experienced professional? etc.).
Then after that you can invest in a game engine textbook/guide to learn the basics of the engine.
I hope this helps, and gives you a starting point. Feel free to ask more questions though.
Best of luck!
