AWS API Gateway {"error": "missing authentication token"} - ios

Question

I've been constantly getting the "missing authentication token" error when I click the AWS API gateway POST method url through the browser. I set "AUTH" as none and it's working totally fine through Postman but not with the browser. The problem is that I'm using swift to trigger the method and it doesn't seem to be reaching the gateway at all (no log on CloudWatch) and I don't think my code is wrong (or maybe it is). If someone could point out what my mistake is or a solution to this problem I'd appreciate it so much.
P.S. My lambda function is working totally fine and I typed in the right URL (one in the code is just for example)
Here's my code:
func postNonceToServer(paymentMethodNonce: String) {
let paymentURL = URL(string: "https://example-url.us-east-1.amazonaws.com/prod/create-transaction")!
var request = URLRequest(url: paymentURL)
request.httpBody = "\(paymentMethodNonce)".data(using: String.Encoding.utf8)
request.httpMethod = "POST"
}

Answer 1

In my opinion, this should be a problem in the URL itself. I can think of:
1- Please make sure that the URL is parsed correctly by printing it to the console and pasting it into the browser URL bar. (I have no idea about swift)
2- Make sure that "execute-api" is included in your "example-url", i.e., before the region.
3- Make sure that OPTIONS method has AUTH as none.
Good luck!

Answer 2

After enabling CORS on my endpoints I was receiving the same error message:
{"message":"Missing Authentication Token"}
Everything checked out, but I consistently received that error. To fix my issue I had to deploy the API. To do that, do the following:
Go to "Amazon API Gateway" console
Click on the API Gateway in question
Click "Resources" and select the root resource, e.g., "/"
Click "Actions" and then "Deploy API"
Select the stage you want to deploy to
Click "Deploy"
Long story short, redeploy the API after you've enabled CORS.

Answer 3

This mostly would be because of CORS issue.
Please enable CORS in you API gateway like below. After enabling CORS please redeploy the API
If you don't have OPTIONS added, please follow below steps (If OPTIONS already there just add CORS),
Create a new OPTIONS method under the /services resource
Create and populate the Access-Control-Allow-Origin/Method/Headers in the OPTIONS method.
Enable CORS like below after creating OPTIONS