I have a masterViewcontroller with the container on it and a 2ndViewController embeded via storyboard in that. I am wondering how to access the 2ndViewController from the masterViewController.
I have seen about using prepare for segue but this doesn't seem to get called for when my viewController in the container is shown. Is there something I need to hook up for it to appear in the prepare for segue function?
Or is there another way to achieve this?
You need to override prepare(for segue: sender:) in the masterViewController class.
The segue needs an identifier in the storyboard. In prepare, you then check if the segue to be prepared for is the one you gave the identifier to via segue.identifier == "yourIdentifier".
Then you can resolve the embedded ViewController as your 2ndViewController like so:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "yourIdentifier" {
let child = segue.destination as! 2ndViewController
}
}
By the way, if you use as!, you're force-unwrapping segue.destination as your 2ndViewController class. If you're not 100% certain this segue will always have that class as it's destination, consider instead using as? to treat child as optional and then doing additional checks for it's existence before attempting to use it.
Related
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
super.prepare(for: segue, sender: sender)
self.delegate = segue.destination as? MenuViewController
print("check_1", self.delegate)
}
#IBAction func openMenu(_ sender: Any) {
performSegue(withIdentifier: "openMenu", sender: sender)
print("check_2", self.delegate)
}
My main ViewController updates values while MenuViewController displays these values. Each time ViewController values are updated, it calls self.delegate.updateValues in MenuViewController. I transition between the two ViewControllers through buttons.
My problem is that it seems like the MenuViewController displayed is a different object than the one stored in self.delegate inside ViewController. Printing the check statements:
check_1 Optional(<Menu.MenuViewController: 0x10161ca10>)
check_2 Optional(<Menu.MenuViewController: 0x10161ca10>)
check_1 Optional(<Menu.MenuViewController: 0x10161dd10>)
May I ask how do I make sure only one instance of MenuViewController is created and stored in self.delegate?
When you add a segue to a storyboard, if you hook up the segue to a specific button/IBAction, you don't need to call performSegue manually, it will be automatically called for you.
You have 2 segues executed, since both the storyboard executes the segue and then you also do it from code by calling performSegue.
performSegue should only be used when your segue isn't directly hooked up to a UI event or if you need to conditionally perform a segue - such as when you have a login button, where depending on the network response, you might execute an error or a login segue.
I have a container view in my Storyboard that displays another view controller that I already programmed and stuff. I want to communicate between the main View Controller and the contained-view controller. I know how to use delegates and I am comfortable with using them, however I normally set up delegates when I initialize a ViewController, however in this case I don't know where to apply this, since the view controller is already there per the storyboard. Normally I would do something like this:
class HomeVC: UIViewController {
func initializeVC() {
resultsVC = self.storyboard?.instantiateViewController(withIdentifier: "resultsView") as! GoalsVC
resultsVC.calcDelegate = self //I set the "HomeVC" as the Delegate since it has all the functions I need
}
}
As mentioned above, since I never really created this view controller via code, I don't know how to assign a delegate (specially setting the delegate to "self" (where Self is the main View Controller)
You can assign delegate in prepareforsegue. Like below code
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if (segue.identifier == "container_segue") {
let controller = segue.destination as! containerController
controller.delegate = self
}
}
When project runs, this method called automatically because we had created segue in the storyboard.
By using segue.identifier you can check for which controller segue is going to happen and accordingly you can achieve your requirement.
As you are using storyboard for container view. There is a segue with embed type. Give this segue a identifier, say MyContainedViewControllerSegueId
Then in prepare(for segue:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "MyContainedViewControllerSegueId" {
// here you get your contained view controller as `segue.destination`
// cast it your subclassed view controller
// use delegate on that subclassed view controller for communication purpose.
}
}
I am woking on an recording APP.
I tried to add navigation controller in my first recording viewcontroller which then could pass filename array to the second viewcontroller using the following function prepare:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
let controller = segue.destination as? MainViewController
controller?.recordArray = recordingArray
self.present(controller!, animated: true, completion: nil)
}
However, when ran in the simulator the navigation bar disappeared in the second controller and Xcode pops out the warning
Thread1: EXC_BAD_ACCESS(code=2,address=0x7fff51edfff8)
Has anyone got any advice?
Thanks!
Don't ever call present(_:animated:completion:) inside prepare(for segue:).
prepare(for segue) is called automatically by the system just before a segue is about to happen to let you prepare the data for sending to the destination viewcontroller or do any other calculations you need to before performing the segue. A segue needs to be set up in Storyboard and it will either be called automatically or if it is a manual segue, you need to call it using perform(segue) and once you do that, the system will call prepare(for segue) for you. You can see why calling another navigation function proves to be problematic, since you are trying to navigate to another viewcontroller using two different methods (segue and present).
If you haven't set up the segue in Storyboard, then you also need to do that, since if it is not set up, let controller = segue.destination as? MainViewController will be nil.
Once you set up the segue in Storyboard, this is how your function should look like:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let controller = segue.destination as? MainViewController {
controller.recordArray = recordingArray
self.present(controller, animated: true, completion: nil)
}
}
You shouldn’t be trying to present a VC in this method, it’s just a place for you to configure the destination VC before the segue presents it
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
guard let controller = segue.destination as? MainViewController else { return }
controller.recordArray = recordingArray
}
I have a tabbed view controller that is associated with two view controllers.
I need to pass an array from the first View Controller to the Second View controller.
In Order to do this I have the following code in my first VC:
override func prepare(for segue: UIStoryboardSegue, sender: Any?)
{
if segue.identifier == "AddItem"
{
if let destinationVC = segue.destination as? SecondViewController
{
destinationVC.toDoList = toDoList
}
}
}
However this is not getting fired when I switch two the second VC using the tab button.
Any ideas as to why this is not getting fired?
This is how my main storyboard looks like:
Main Storyboard
You cannot transfer objects between tab views through segue because the VC is not actually making a direct segue connection rather you can do it with a delegate or a notificationCenter post and observe to transfer
You have to put that segue code in Tabbar controller class. You shouldn't put that thing in firstVC. Because there is no segue is going on from first VC to Second VC.
So I have multiple buttons on one view segue'ing to other views. I have the function prepareForSegue() at the bottom of my code preparing one segue, however the app crashes when I use another segue on the view, even if it doesn't need any preparing.I think that the problem is that all of the segues use the prepareForSegue() function, however the storyboard ID is different than the view it is transitioning to.Is there any way to specify a prepareForSegue() function for each separate segue on the same view?Code:
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
let theVC: ViewController = segue.destinationViewController as! ViewController
theVC.receivedString = "true"
}
Thanks
In your prepareForSegue you should use a condition to check segue identifier like:
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if(segue.identifier == "yourSegueToAnyController")
{
//do code for specific viewController
}
}