Mysterious Network issues with posts. Wifi Works, Cell doesn't - ios

Question

I keep getting a timeout with sending post requests when my actual device is on 3G or 4G. However, when I'm on wifi, the post request is immediately received on the server side.
Here's my code that involves the post request. I'm getting a Optional("The request timed out."). I don't think the session length should be a problem since it times out after a long time and the data that is being sent is just a username with a password. Any thoughts?
I run a flask server, but I don't think it's relevant so I didn't include its code.
if let jsonData = try? JSONSerialization.data(withJSONObject: dict, options: .prettyPrinted) {
let url = NSURL(string: base_address + taglocation_address)!
let request = NSMutableURLRequest(url: url as URL)
request.httpMethod = "POST"
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
request.httpBody = jsonData
print("starting task")
let task = URLSession.shared.dataTask(with: request as URLRequest){ data,response,error in
if error != nil{
self.statusLabel.text = error?.localizedDescription
print(error?.localizedDescription)
return
}
do {
let json = try JSONSerialization.jsonObject(with: data!, options: JSONSerialization.ReadingOptions.allowFragments) as? NSDictionary
print("doing something")
if let responseJSON = json as? [String: String] {
print(responseJSON)
self.statusLabel.text = responseJSON["status"]
}
} catch let error as NSError {
self.statusLabel.text = error.localizedDescription
print(error)
}
}
task.resume()
}

Answer 1

In your NSMutableURLRequest object, try adding allowsCellularAccess property and set it to true. Refer to my code below.
if let jsonData = try? JSONSerialization.data(withJSONObject: dict, options: .prettyPrinted) {
let url = NSURL(string: base_address + taglocation_address)!
let request = NSMutableURLRequest(url: url as URL)
request.httpMethod = "POST"
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
request.httpBody = jsonData
request.allowsCellularAccess=true //Add this line
print("starting task")
let task = URLSession.shared.dataTask(with: request as URLRequest){ data,response,error in
if error != nil{
self.statusLabel.text = error?.localizedDescription
print(error?.localizedDescription)
return
}
do {
let json = try JSONSerialization.jsonObject(with: data!, options: JSONSerialization.ReadingOptions.allowFragments) as? NSDictionary
print("doing something")
if let responseJSON = json as? [String: String] {
print(responseJSON)
self.statusLabel.text = responseJSON["status"]
}
} catch let error as NSError {
self.statusLabel.text = error.localizedDescription
print(error)
}
}
task.resume()
}