how to declare NFCReadersession variable in main class when NFC delegate method are implemented using extension?

Question

Well, I need to add NFC functionality to a project and for this I am using CoreNFC. There is a condition that I need to add NFC functions using extension as below:

extension scanVC: NFCNDEFReaderSessionDelegate {
    func readerSession(_ session: NFCNDEFReaderSession, didInvalidateWithError error: Error) {
    }
    func readerSession(_ session: NFCNDEFReaderSession, didDetectNDEFs messages: [NFCNDEFMessage]) {
    }
}

and rest of the code of view controller scanVC is also implemented using extensions like so:

extension scanVC {
    override func viewDidLoad() {
        super.viewDidLoad()
      //viewDidLoad code here
    }

 override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
     //viewWillAppear Code here
}
override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        // viewWillDisappear code here
    }

   override func viewDidDisappear(_ animated: Bool) {
        super.viewDidDisappear(animated)
//viewDidDisappear code here
}
override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
 // code here
    }

}

extension scanVC: SubmitForm {
    // some other functionalities 
}

// *** main class with some variable and outlets declaration ***
class scanVC: UIViewController {

    @IBOutlet var headerScanLabel: UILabel!
    @IBOutlet var scanView: UIView!
    @IBOutlet var scanLabel: UILabel!
    @IBOutlet var submitBtn: UIButton!
}

well now the problem is I need to declare one or more session variables in this main scanVC, but when I declare it gives me an error relating @available as: " 'NFCReaderSession' is only available on iOS 11.0 or newer " if I fix it adding "@available(iOS 11.0, *)" to its enclosing class then the extension with viewdidload,viewWillappear etc gives this error :

"Overriding 'viewDidLoad' must be as available as declaration it overrides"

I have spent almost a day to fix but nothing worked... any suggestion?? Xcode 10.2, swift 4. thanks!!

Hi, try this one - https://stackoverflow.com/questions/46438268/swift-4-0-overriding-prepare-must-be-as-available-as-declaration-it-overrides — shbedev, Dec 12 '19 at 17:03

score 0 · Accepted Answer · answered Dec 21 '19 at 05:01

Well the solution was easy... I just declared those required variable out of class.. just below import statement. And they are accessible in all extension blocks.

//***********NFC REQUIRED VARIABLES *************
@available(iOS 11.0, *)
var nfcsession:NFCNDEFReaderSession?
@available(iOS 11.0, *)
var detectedMessages = [NFCNDEFMessage]()
@available(iOS 11.0, *)
var payloads = [NFCNDEFPayload]()
//************************************************

how to declare NFCReadersession variable in main class when NFC delegate method are implemented using extension?

1 Answers1