swift how to push data to other view by dismissing the current viewcontroller?

Question

I am trying to push some data back to the previous view controller ( Let's call this AViewController ) from my current one ( Let's call this BViewController )

however, when I use performSegue method it shows me the AViewController I wanted but makes the tab bar controller at the botton of the screen disappear (iirc this is because it creates a new "view" with the performSegue method?)

but when I use the dismiss method no data is passed back (neither in the completion with self.performSegue)

So how do I push my data back to AViewController while still have my tab bar controller at the bottom?

Here's my code

 // Push data to AViewController
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    var aViewController = segue.destination as? AViewController
    if routineReps.isEmpty == false {
        for i in 0...routineReps.count-1 {
            routineViewController?.workOutNameArray.append(routineNames[i])
            routineViewController?.workOutSetsArray.append(routineSets[i])
            routineViewController?.workOutRepsArray.append(routineReps[i])
        }
    }
}

 // Button Action to push data back to previous viewcontroller
 @IBAction func completeAddingWorkoutButton(_ sender: UIButton) {

    self.performSegue(withIdentifier: "addWorkoutsForTodaySegue", sender: self)
 }

Look into unwind segues https://developer.apple.com/library/content/technotes/tn2298/_index.html — Malik, Jan 12 '18 at 05:39
@Tj3n how do I use delegate to push back my data? Sorry I am still very new to swift and ios development — porkchopbento, Jan 12 '18 at 05:45
@porkchopbento Make sure you only right the code in either `prepareForSegue` or the method that the unwind segue unwinds to. Not both — Malik, Jan 12 '18 at 06:13
@Malik found and fixed the problem and got it to work. Thanks! — porkchopbento, Jan 12 '18 at 06:13

score 4 · Answer 1 · answered Jan 12 '18 at 06:00

As mentioned you can use Delegates or NSNotificationCenter or Singleton Patterm

Scenario is you navigate from Class A to Class B and now want to pass data from Class B to A while you come back to Class A, you want to have that passed data

 Class A -> Navigates -> Class B
       <- Sends Data back

Delegate -

Define a protocol in Class B

Class BViewController

 @objc
 protocol ClassBDelegate {
      func passingSomeValue(val : String)
  }

  class BViewController{
        weak var delegate : ClassBDelegate! //define a variable of the protocol
       func passValueWhenFromThisMethod(){
             let someString = "this value will get passed"
              delegate.passingSomeValue(someString)
              self.navigationController?.popViewController(animated: true)
        }
  }

Class AViewController

  class AViewController{
        override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
      if let segue.identifier = "segueidentifierforgoingtoclassBVC"{
           var classBVC = segue.destinationViewController as! BViewController
             classBVC.delegate = self
       }
  }
   }

  extension AViewController : ClassBDelegate{
    func passingSomeValue(val : String){
         print("Got this value from Class B: \(val)")
     }
   }

score 0 · Answer 2 · answered Jan 12 '18 at 06:03

0

use delegate to pass data to previous ViewController following the method given in link below:

Passing data back from view controllers Xcode

answered Jan 12 '18 at 06:03

Asim Iftikhar Abbasi

547
1
5
16

You better add it as an comment, use comment section for giving link – karthikeyan Jan 12 '18 at 06:14

swift how to push data to other view by dismissing the current viewcontroller?

2 Answers2