How to check whether in subscription or not in iOS - ios

Question

I implemented subscription (auto renewable purchase). I want to check whether the user is still subscribed or not when my app launched ever time. I tried to use the below code but it returns always "success" even if user is not subscribed.
How can I check the user subscription status?
func receiptValidation() {
let SUBSCRIPTION_SECRET = "password"
let receiptPath = Bundle.main.appStoreReceiptURL?.path
if FileManager.default.fileExists(atPath: receiptPath!){
var receiptData:NSData?
do{
receiptData = try NSData(contentsOf: Bundle.main.appStoreReceiptURL!, options: NSData.ReadingOptions.alwaysMapped)
}
catch{
print("ERROR: " + error.localizedDescription)
}
//let receiptString = receiptData?.base64EncodedString(options: NSData.Base64EncodingOptions(rawValue: 0))
let base64encodedReceipt = receiptData?.base64EncodedString(options: NSData.Base64EncodingOptions.endLineWithCarriageReturn)
print(base64encodedReceipt!)
let requestDictionary = ["receipt-data":base64encodedReceipt!,"password":SUBSCRIPTION_SECRET]
guard JSONSerialization.isValidJSONObject(requestDictionary) else { print("requestDictionary is not valid JSON"); return }
do {
let requestData = try JSONSerialization.data(withJSONObject: requestDictionary)
let validationURLString = "https://sandbox.itunes.apple.com/verifyReceipt" // this works but as noted above it's best to use your own trusted server
guard let validationURL = URL(string: validationURLString) else { print("the validation url could not be created, unlikely error"); return }
let session = URLSession(configuration: URLSessionConfiguration.default)
var request = URLRequest(url: validationURL)
request.httpMethod = "POST"
request.cachePolicy = URLRequest.CachePolicy.reloadIgnoringCacheData
let task = session.uploadTask(with: request, from: requestData) { (data, response, error) in
if let data = data , error == nil {
do {
let appReceiptJSON = try JSONSerialization.jsonObject(with: data)
print("success. here is the json representation of the app receipt: \(appReceiptJSON)")
// always through here
} catch let error as NSError {
print("json serialization failed with error: \(error)")
}
} else {
print("the upload task returned an error: \(error)")
}
}
task.resume()
} catch let error as NSError {
print("json serialization failed with error: \(error)")
}
}
}