Swift 5 timer countdown, while a value is in a range - swift

Question

I am trying to Countdown from, say, 5 to 0 WHILE the users bearing is between 20 and -20 radian from true north. If bearing remains between 20 and -20 for 5 seconds, segue to new controller. I've tried everything and I have mostly given up.
I've tried a bunch of things, including scheduleTimer(withInterval 1.0){}
I am new to Swift. I was unable to invalidate timer.
Here is the getting user heading
#objc func getUserHeading(_ latitude : Double, _ longitude : Double, _ userLocation : CLLocation){
let lat1 = (latitude) * .pi / 180
let long1 = (longitude) * .pi / 180
let lat2 = (yourLocation.coordinate.latitude) * .pi / 180
let long2 = (yourLocation.coordinate.longitude) * .pi / 180
print(lat1, long1, lat2, long2)
let dLon = long2 - long1
let y = sin(dLon) * cos(lat2)
let x = cos(lat1) * sin(lat2) - sin(lat1) * cos(lat2) * cos(dLon)
var radiansBearing = atan2(y, x)
if radiansBearing < 0 {
radiansBearing += 2 * Double.pi
}
theta = (radiansBearing * 180 / .pi) - (angle)
print(theta)
if (theta < 20 && theta > = -20 ){
timer = Timer.scheduledTimer(withTimeInterval: 1.0, repeats: true) { timer in
print("Timer Fired")
runCount += 1
if(theta > 20 && theta < -20)
{
self.timer.invalidate()
self.timerStarted = false
}
if (runCount == 5)
{
self.timer.invalidate()
self.segueToNewController()
}
}
else{
timer.invalidate()
timerStarted = false
}
}
This is probably a semantics thing, but I swear I have spent DAYS on this and I feel like I am getting no where.
Issues so far
It does trigger when between 20 and -20 but it triggers immediately and doesn't wait for 5 seconds
It triggers MANY times, which means the segue for the next controller is called many times (it caused like 5k writes to my firestore)
If you guys need anything more, please do let me know, will update question with more code.
All help appreciated! End of my wits here

Answer 1

There are some issues with your code
You have 2 contradicting if clauses, first you check if theta is inside the interval and then inside the if clause you check if the same value is outside the interval which will never happen.
The last else looks misplaced
There are variables you change but never read
I would rewrite it something like this (from the first if)
if theta < 20 && theta >= -20 {
timer = Timer.scheduledTimer(withTimeInterval: 1.0, repeats: true) { timer in
print("Timer Fired")
runCount += 1
if runCount == 5 {
timer.invalidate()
}
//theta = ... here you need to somehow update this property to see if it has changed
if theta > 20 && theta < -20 {
timer.invalidate()
}
}
} else {
timer?.invalidate()
}
Note that I removed the timerStarted variable because I didn't see the point of having it and also not that parentheses are not needed around if conditions