how to iterate through functions with button press in Swift

Your code should like this :

// You can define this variable globally...
var counter = 0
@IBAction func nextAnimation(_ sender: UIButton) {
    if (counter == 0) {
        funcAnimation1()
        // Increase counter count by 1 and you can add this line to completion of animation.
       // You can also disable your button interaction until your animation gets complete and that way you can handle your UI
        count += 1
    }
    else if (counter == 1) {
        funcAnimation2()
         // Increase counter count by 1 and you can add this line to completion of animation.
        count += 1
    }
    else if (counter == 2) {
        funcAnimation3()
        // set your counter to 0 again to loop through your animation.
        counter = 0
    }
}

Your Back Action should look like this:

@IBAction func backAnimation(_ sender: UIButton) {
    if (counter == 0) {
        funcAnimation1()
        // set your counter to 2 again to loop through your animation.
        count = 2
    }
    else if (counter == 1) {
        funcAnimation2()
        // decrease counter count by 1 and you can add this line to completion of animation.
        // You can also disable your button interaction until your animation gets complete and that way you can handle your UI
        count -= 1
    }
    else if (counter == 2) {
        funcAnimation3()
       // decrease counter count by 1 and you can add this line to completion of animation.
        count -= 1
    }
}