Custom Time Formatter in TextField

I have a TextField that defaults it’s value to 00:00.0 . If a user were to click on the field and start typing, as it is right now if they would type a 7 the value would display 700:00.0 . I want the typing to overwrite the value, from left to right, such that if a user types a 7 then the value would be 00:00.7 and then if they type a 6, 3, 4, 3, 6 in that order it would be 763:43.6. It seems like using a formatter is my best bet for something like this, but I am new to SwiftUI and haven’t used a formatter before, can someone help point me in the right direction to get started?