unexpectedly found nil while unwrapping an Optional value On UILabel

Question

In my project I have implemented a protocol which makes some URL call and return result, and my intent is to show result in UILabel. Following is my code :

protocol RestAPIResult
{
   func retriveDriverInfo()
}

class RestAPICall :  RestAPIResult
{
   func retriveDriverInfo()
    {
     self.dashBoardViewController.getDriverInfo(driverProfile)
    // calling another function of Next View for Lable Setup
    }
}

getDriverInfo is in NextView which has Outlet of textVIew

class DashBoardViewController: UIViewController
{
       override func viewDidLoad()
        {
        super.viewDidLoad()

        restDeledate = RestAPICall()

        restDeledate!.retriveDriverInfo()
     // IF LABEL SET HERE NO ERROR
      //totalTripLabel.text = "Testing"  // NO ERROR

        }

       func getDriverInfo(driverInfoArray : NSArray)
       {
        totalTripLabel.text = "Testing" // HERE IS ERROR
       }

}

If Text is set in ViewDidLoad() it doesn't crash. but when i tried to set value in delegate function it crash saying found null.

The view isn't loaded yet, thus the UILabel is nil. You should go over UIViewController lifecycle to understand more. — orxelm, Jun 11 '16 at 07:49
@orxelm is correct. See this answer: http://stackoverflow.com/questions/5562938/looking-to-understand-the-ios-uiviewcontroller-lifecycle — Grimxn, Jun 11 '16 at 08:43

score 0 · Answer 1 · answered Oct 10 '18 at 04:47

protocol RestAPIResult: NSObjectProtocol
    {
       func retriveDriverInfo(message: String)
    }

    class RestAPICall :  RestAPIResult
    {

    override func viewDidLoad()
            {
            super.viewDidLoad()
             //create an instance of your vc and
            instance.delegate = self
            //if you code for push vc then write this line there  insatance.delegate = self
            }
       func retriveDriverInfo(message: String)
        {
         yourLbaelOutlet.text = message
        }
    }


    class DashBoardViewController: UIViewController
    {
           weak var delegate: RestAPIResult!

           override func viewDidLoad()
            {
            super.viewDidLoad()
            }

           func getDriverInfo(driverInfoArray : NSArray)
           {
            self.delegate.retriveDriverInfo(message: "youMessage")
           }

    }

*

unexpectedly found nil while unwrapping an Optional value On UILabel

1 Answers1