Passing Data between interface controllers in WatchKit

Question

How would I pass data stored in a label from my Interface Controller to another interface controller in WatchKit using Swift? I can't seem to find an answer anywhere, hope someone here can help me. I've included the section of my code that deals with calculating the value I need passed. I basically want to show the same value that was calculated by the user and elaborate more on it in the next Interface Controller named ResultsController. Any help is greatly appreciated :D

class InterfaceController: WKInterfaceController {
     var currentValue: String = "0"

     func setDisplayValue(value: Double)
    {
        var percent = value
        //  check if value is an integer
        if value % 1 == 0
        {
            // our value is an integer
            currentValue = "\(Int(value))"// new value %
        }
        else
        {
            // our value is a float
            currentValue = "\(value)"
        }
        // Display 2 decimal places in final amount
       var round =  NSString(format:"%.2f", value)
        displayLabel.setText("$\(round)") // Display final value
        // This value is what I want to be passed to another label in another IC.
    }

    // Answer Tapped
    @IBAction func totalTapped() {
        if command != nil
        {
            let answer = command!.executeWithNewValue((currentValue as NSString).doubleValue)
            setDisplayValue(answer)
            command = nil
            calculationExecuted = true
        }
    }
}

This is the second Interface controller that I want the value from the first one to be displayed in using a label.

import WatchKit
import Foundation


class ResultsController: WKInterfaceController {

    @IBOutlet weak var totalLabel: WKInterfaceLabel!

    override func awakeWithContext(context: AnyObject?) {
        super.awakeWithContext(context)

        // Label to hold the same value as in previous Interface Controller
        totalLabel.setText("")
    }

    override func willActivate() {
        // This method is called when watch view controller is about to be visible to user
        super.willActivate()
    }

    override func didDeactivate() {
        // This method is called when watch view controller is no longer visible
        super.didDeactivate()
    }

}

Edit: Here is the tutorial I followed, I manipulated it a bit to be essentially a tip cal. I added in ResultsController to hold the information inputted by the user using the calculator from InterfaceController but I can't seem to pass the data over to my labels in RC, in the Command I removed subtract and divide since I wouldn't be needing those. So the only calculation buttons I have are multiply and addition. Example of how it should work: Enter in an amount 12.58 tap multiply and enter in 15 tap add and it displays the final amount of 14.46 I need to pass over all of those values to RC in separate labels.

Github Tutorial - Apple Watch

Here is what I am trying to accomplish: Passing the initial amount to a label, and the tip amount, as well as the final cost to separate labels to resemble a bill.

score 19 · Answer 1 · answered Apr 02 '15 at 02:24

The best way to do this is to override the contextForSegueWithIdentifier method that is called when you segue from one view to the next.

The method of passing data between WKInterfaceControllers is a bit different than the method for doing so with UIViewControllers in a traditional iOS app.

Normally, you'd do something like this:

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    if segue.identifier == "showDetail" {
        let controller: DetailViewController = (segue.destinationViewController as UINavigationController).topViewController as DetailViewController
        controller.myVariable = myValue
    }
}

However, there is no prepareForSegue method in WatchKit. The contextForSegueWithIdentifier WKInterfaceController method is similar, but it has a glaring difference: it doesn't provide you with an instance of the destination view controller.

Instead, you return data from the method, and access that data within your target class.

So, in your case, it would look like this:

// In InterfaceController
override func contextForSegueWithIdentifier(segueIdentifier: String) -> AnyObject? {
    // You may want to set the context's identifier in Interface Builder and check it here to make sure you're returning data at the proper times

    // Return data to be accessed in ResultsController
    return self.currentValue
}

// In ResultsController
override func awakeWithContext(context: AnyObject?) {
    super.awakeWithContext(context)

    // Make sure data was passed properly and update the label accordingly
    if let val: String = context as? String {
        self.totalLabel.setText(val)
    } else {
        self.totalLabel.setText("")
    }
}

Thanks for answering, AstroCB, my app is basically a calculator so currentValue is constantly changing, which the previous code you posted only displayed the last value entered by the user. How would I save the first value entered and pass that over to a label ResultsController, and also pass the value being added, mult, div, or subtracted to a different label in ResultsController, and finally passing over the "answer" to a different label? Sorry for all the questions lol — adrlan, Apr 02 '15 at 04:02
@adrlan It's no problem; if you want to pass multiple values, you can return a dictionary, like this `var dict: [String: Int] = ["added": addedVal, "subtracted": subtrVal]` (etc.) and then you can access it in Results like this: `if let dict: [String: Int] = context as? [String: Int] { let added: Int = dict["added"] }`. — AstroCB, Apr 02 '15 at 04:10
What about the other way around? From `ResultsController` to `InterfaceController` — Nico, Apr 04 '17 at 23:58

score 15 · Answer 2 · edited Nov 25 '16 at 07:18

15

Use pushControllerWithName:context: or presentControllerWithName:context:

NSDictionary *exampleObj = @{@"key":@"value"};
[self pushControllerWithName:@"YourInterfaceControllerName" context:exampleObj];

On the receiving end, use awakeWithContext:context

- (void)awakeWithContext:(id)context
{
    [super awakeWithContext:context];
    NSString *value = context[@"key"];
}

As context is an (id), you can pass anything, not just NSDictionary.

edited Nov 25 '16 at 07:18

emotality

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answered Jun 09 '15 at 16:55

bhautikmewada191

653
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Was this down voted because it doesn't work, or because it is bad practice? – Eagle11 Jun 23 '15 at 18:02
I like this method. Easy and simple. context is type of id, so you can pass anything in there. Nice! – GeneCode Aug 19 '16 at 07:53
how to access that "context" on next interface controller? – Jan 22 '17 at 13:26
1

What about the other way around? From `ResultsController` to `InterfaceController` – Nico Apr 04 '17 at 23:58

score 3 · Answer 3 · answered Jun 06 '21 at 10:40

for swift 5, use pushController

A scene -> B scene

1.set your scene name . (look at the red circle)

from controller to be like the below. put the scene name(red circle) that you want to move to as first argument. and second argument is your data that you want to send to the next controller


    AinterfaceController.swift
    (@IBAction) func changeScene(){
       self.pushController(withName: "next scene identifier: the name that u set in the red circle", context: yourData)
    
    }

"To" controller to be like the below.

    BinterfaceController.swift
    ...
        override func awake(withContext context: Any?) {
            super.awake(withContext: context)
            print("what you send from A controller", context)
            
        }

Passing Data between interface controllers in WatchKit

3 Answers3

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