iOS Swift storing simple data globally

Question

New to iOS development and trying to develop my app with correct practices. My main issue is trying to figure out the best way to store a bunch of simple data globally.

The app connects to a computer adhoc wifi and gathers information about the current state. (ex// gpu temp, computer name, display resolution, date/time, etc). The various view controllers I have then allow the user to adjust some of these settings so I want to be able to keep track of these changes across all view controllers.

I have been wrestling between using a plist, core data, or singleton class to store all the information. Since the user will be connected to one computer for the life of the app I am leaning towards singleton since it seems easiest to get and set data. However, I have read that using a singleton is really not the best practice for various reasons. I have read up on plists and core data a little and seems like a decent amount of work just to get and set values. Should I spend the time using those or would some other method be a better way to accomplish all of this.

Update: After both answers from Aaoli and Swift Rabbit. I wanted to clarify for my use case that the data I am storing did not need to be "saved" when the app was closed. So if you are coming to this question and need to store your data even if the app closes look at @SwiftRabbit's answer.

Answer 1

To use Global variable in Swift you need to define struct outside the class and because you don't need the variable to be swimming in the whole app memory without binding:

struct GlobalVar {
    static var myvar = 0

}

To use simply the global variable from anywhere use :

GlobalVar.myvar = 10