Centralized token for concurrent asynchronous network tasks - ios

Question

I have an application that is pulling API data for multiple tasks within itself.
The main API data request is to pull the appointments for a given provider or location in our health system.
To have the proper keys to match the provider ID or location ID to the actual name, I pull that data from the API as well to make sure they are up to date.
I have it working so the network call checks if the current API token is active, and if not, automatically refreshes it and re-calls the network data. Once the token is confirmed to either be currently active OR to be refreshed properly, it returns true.
However, the 3 different network pulls are calling data asynchronously and one will update the API token while the other is attempting to do the same and then the API token gets updated repeatedly within the same sequence unnecessarily.
To fix this, I am attempting to switch to a localized token function which checks if the current token is active, and if not refreshes it. It also checks if there is a token update already in progress, and if so stops the other functions from updating it as well. It also re-calls the original function in order to wait for the updated token to appear.
The problem I'm running into is I seem to have created a loop that crashes my app before the new token can appear. Essentially what I'm guessing I need to solve this is to wait for a response before re-calling the loop, but I'm unsure on the best way to do this.
Here is my token check/refresh code:
My model also has a var tokenUpdateInProgress = false so that the new function can alert when a new update begins.
func isTokenActiveAndRefreshIfNot(_ completion: #escaping (Bool) -> ()) {
print("running tokenActive function")
var returnBool = false
print("tokenUpdateInProgressz: \(tokenUpdateInProgress)")
if tokenUpdateInProgress == false {
print("no other update in progress, start the check here")
tokenUpdateInProgress = true
let resourceListURL = "https://api.carecloud.com/v2/oauth2/token_info"
var request = URLRequest(url:URL(string:resourceListURL)!)
request.addValue("Bearer \(token)", forHTTPHeaderField: "Authorization")
request.httpMethod = "GET"
var json = JSON()
URLSession.shared.dataTask(with: request){ data, response, error in
print("data pull called in isTokenActive")
if let httpResponse = response as? HTTPURLResponse {
print("status code: \(httpResponse.statusCode)")
httpStatusCode = httpResponse.statusCode
}
if httpStatusCode == 200 {
print("token is current, proceed")
tokenUpdateInProgress = false
returnBool = true
json = try! JSON(data: data!)
for (_, _) in json {
if let expiration = json["expires_in"].string {
if let double = Double(expiration) {
let dateTime = Date()
let newDateTime = dateTime.addingTimeInterval(double)
tokenExpiresDateTime = newDateTime
}
}
}
}
if httpStatusCode == 403 || httpStatusCode == 401 {
let downloadGroup = DispatchGroup()
print("token is expired, need to refresh it")
tokenUpdate = false
downloadGroup.enter()
refreshToken({ (tokenRefreshed) in. //this function refreshes my token successfully
if tokenRefreshed == true {
//can do something here if token refresh works correctly
returnBool = true
tokenUpdateInProgress = false
downloadGroup.leave()
downloadGroup.notify(queue: DispatchQueue.main) {
// completion(returnItem)
}
}
})
}
completion(returnBool)
}.resume()
} else if tokenUpdateInProgress == true {
print("token update in progress, re-run check and wait for result")
isTokenActiveAndRefreshIfNot { (result) in //this creates a loop if network not working or token refresh not working for any reason. This loops too fast and leads to a crash.
returnBool = result
}
completion(returnBool)
}
}
The three functions all pulling this data are:
1:
func monthSchedule(resourceID: String, locationID: String, page: Int, _ completion: #escaping ([appt]) -> ()){
isTokenActiveAndRefreshIfNot { (tokenUpdated) in
print("token update within monthschedule: \(tokenUpdated)")
}
... runs network pull/API interpretation from token once confirmed ok
}
2:
func pullLocationsList(_ completion: #escaping ([Int: String]) -> ()){
isTokenActiveAndRefreshIfNot { (tokenReady) in
print("token ready for pull location list: \(tokenReady)")
}
... runs network pull/API interpretation from token once confirmed ok
}
3:
func pullResourceList(_ completion: #escaping ([Int: String]) -> ()){
isTokenActiveAndRefreshIfNot { (tokenReady) in
print("token ready for pull resource list: \(tokenReady)")
}
... runs network pull/API interpretation from token once confirmed ok
}