I have an optional bool
variable called showSettings
on my first view controller which is called ViewController
, and I'm popping from SecondViewController
back to ViewController
.
Before I pop, I want to set the bool to true. Seems wrong to instantiate another view controller since ViewController
is in memory.
What's the best way to do this? I'm not using storyboards, if that's important for your answer.
Thanks for your help
To pass data back, the most common approach is to create a delegate property in your detail view controller, like this: class ViewControllerB: UIViewController { var selectedName: String = "Anonymous" weak var delegate: ViewControllerA! }
So I figured it out, based mostly from this post – http://makeapppie.com/2014/09/15/swift-swift-programmatic-navigation-view-controllers-in-swift/
In SecondViewController
, above the class declaration, add this code:
protocol SecondVCDelegate {
func didFinishSecondVC(controller: SecondViewController)
}
Then inside of SecondViewContoller
add a class variable:
var delegate: MeditationVCDelegate! = nil
Then inside of your function that your button targets, add this:
self.navigationController?.popViewControllerAnimated(true)
delegate.didFinishSecondVC(self)
What we're doing here is doing the pop in SecondViewController
, and not passing any data, but since we've defined a protocol, we're going to use that in ViewController
to handle the data.
So next, in ViewController
, add the protocol you defined in SecondViewController
to the list of classes ViewController
inherits from:
class ViewController: UIViewController, SecondVCDelegate { ... your code... }
You'll need to add the function we defined in the new protocol in order to make the compiler happy. Inside of ViewController
's class, add this:
func didFinishSecondVC(controller: SecondViewController) {
self.myBoolVar = true
controller.navigationController?.popViewControllerAnimated(true)
}
In SecondViewController
where we're calling didFinishSecondVC
, we're calling this method inside of the ViewController
class, the controller we're popping to. It's similar to if we wrote this code inside of SecondViewController
but we've written it inside of ViewController
and we're using a delegate to manage the messaging between the two.
Finally, in ViewController
, in the function we're targeting to push to SecondViewController
, add this code:
let secondVC = secondViewController()
secondVC.delegate = self
self.navigationController?.pushViewController(secondVC, animated: true)
That's it! You should be all set to pass code between two view controllers without using storyboards!
_ = self.navigationController?.popViewController(animated: true)
let previousViewController = self.navigationController?.viewControllers.last as! PreviousViewController
previousViewController.PropertyOrMethod
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