I have 2 buttons in a view controller. If button 1 is clicked, then go to WebView controller. If button 2 is clicked then go to ArtView controller.
How to make override func prepare(for segue: UIStoryboardSegue, sender: Any?) have 2 destinations depending on the button clicked?
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let destination = segue.destination as? WebViewController {
// your code
}
if let destination = segue.destination as? ArtViewController {
// your code
}
}
Hope it will help! :)
Have each button invoke a different segue, either by control-dragging segues directly from the button, or by calling performSegue(withIdentifier:sender:) from your buttons' IBAction code.
Then use code in prepare(for:sender:) to figure out which destination is being invoked.
You can:
Check the identifier on the segue (not recommended - fragile)
Check the class of the destination view controller (better than 1)
Have each view controller implement a protocol and check the protocol of the destination:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
switch segue.destination {
case let webView as WebViewProtocol:
//Your code for a web view
case let artView as ArtViewProtocol:
//Your code for an Art View
}
}
Option 3 is reliable while providing loose coupling (each case can trigger any view controller that conforms to the desired protocol. All it needs to know is that the destination understands the desired protocol.)
Related
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'm using a Page View Controller to implement an image carousel in my app. I have a container view in my parent view controller which has an embed segue to the Page View Controller. The problem I'm having is when I need to go off and fetch these images asynchronously and the segue happens before viewDidLoad gets the images.
My prepare for segue:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "startCarousel" {
let carouselPageViewController = segue.destination as! CarouselPageViewController
carouselPageViewController.images = carouselImages
}
}
in viewDidLoad:
GalleryManager.sharedInstance.getData = {
(data) in
// Assign images to instance property here ...
}
My thinking is that once I get the images that I programmatically start the segue myself. Or if I should be doing this a different way any advice would be much appreciated.
You can do something like, return false in shouldPerformSegue and initiate segue when data is loaded
i.e.
override func shouldPerformSegue(withIdentifier identifier: String, sender: Any?) -> Bool {
if identifier == "startCarousel" {
return (detail != nil)
}
return true
}
Then in viewDidLoad
GalleryManager.sharedInstance.getData = { [weak self]
(data) in
self?.performSegue(withIdentifier: "startCarousel", sender: nil)
}
No, you can't delay an embed segue. If you use an embed segue it fires as soon as the view controller is loaded.
You need to wait until the data loads and then call the setViewControllers(direction:animated:completion) to install the view controllers that you will use to display the data once the data is loaded.
Swift 3, Xcode 8
You can realize in this way:
set a reference to your page view controller in prepareForSegue in your masterViewController:
var myContainerViewController: UIPageViewController?
override func prepare(for segue: UIStoryboardSegue, sender: Any?)
{
if segue.identifier == "embedSegue" {
if let destination = segue.destination as? YourPageViewControllerClass {
self.myContainerViewController = destination
}
}
Define a function in your own pageViewController class:
func someFunction(){
//configure your image or swipe page
}
when you get the images, in your masterViewController call:
self.myContainerViewController?.someFunction()
you can't delay an embed segue.
you try to put button in view controller and then after view load set button click to set image...
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
}
}