I have a Custom Segue exhibiting a view controller, and then have a corresponding Custom Unwind Segue. This code has worked fine in iOS 8, and is implemented by engendering subclasses of UIStoryboardSegue and implementing the perform method. Then I override the following method in my custom Navigation Controller
func segueForUnwindingToViewController(toViewController: UIViewController, fromViewController: UIViewController, identifier: String) -> UIStoryboardSegue {
var segue: UIStoryboardSegue
if (fromViewController is MyViewController.self) {
segue = CustomSegue(identifier: identifier, source: fromViewController, destination: toViewController)
//Custom Unwind Segue
}
else {
var unwindSegue: UIStoryboardSegue = super.segueForUnwindingToViewController(toViewController, fromViewController: fromViewController, identifier: identifier)
//Normal Unwind Segue
segue = unwindSegue
}
return segue
}
In iOS 9, segueForUnwindingToViewController is deprecated. It still works for the MyViewController CustomSegue; however, the default unwind segue no longer works for any other unwind segue. Although calling the method on super returns an unwind segue, the segue never occurs, the view controller is never popped, and the user can never go back to the previous screen. So just to be clear, if I use a regular show segue, the corresponding unwind segue calls the deprecated method, which calls the method on super, and does not work.
If Controller B unwinds to controller A, then in controller A:
#IBAction func viewController-B-DidExit(segue: UIStoryboardSegue) {
let controller = segue.sourceViewController as! viewController-B
}
Then in viewContoller B connect the object you want to exit from to the exit.
Related
Learning some view controller basics and am stuck on how to dismiss a modal with a button.
In my slimmed-down example, I have a two view setup with the initial view and the modal. The first view has a button that successfully pops up the modal. On the modal, there is a button that should dismiss itself.
According to other posts and documentation, I should be able to run simple code attached to the button like this:
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
}
#IBAction func CloseModal(_ sender: Any) {
self.dismiss(animated: true, completion: nil)
}
}
When I tap the "Close Modal" button nothing happens. What am I missing here? Am I putting this code in the wrong place? Currently, it's in the main ViewController.swift file.
The other approach is to use an unwind segue to your main view controller. Just add an “unwind action” in the first view controller:
class ViewController: UIViewController {
#IBAction func unwindHome(_ segue: UIStoryboardSegue) {
// this is intentionally blank
}
}
Just give this unwind action a meaningful name, unwindHome in this example, so that, if and when you have multiple unwind actions later on, you can easily differentiate between them.
Then you can control-drag from the button in the second scene to the “exit” control and select the appropriate unwind action:
This has a few nice aspects:
The “close” button no longer cares how you presented it, it will unwind however is appropriate (e.g. if you later change the initial segue to be a show/push segue, the unwind segue will still work without any code changes).
Because you’re now using a segue to unwind, the presented view controller can use its prepare(for:sender:) to send data back, should you eventually need to do that.
If you want, you can unwind multiple scenes. For example if A presents B, and B presents C, you can obviously unwind from C to B, but you can also unwind all the way from C to A if you want.
So, while dismiss works, unwind segues are another alternative.
You actually have two ViewController screens, but it looks like you have one ViewController class? And is the 2nd screen connected to a class?
Must be in the class that belongs to the second screen of the closeModal method.
//This is First ViewController, OpenModal Button is here
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
}
}
// The name of the class and the Viewcontroller in the storyboard have to be the same, and CloseModol Button and function need to be here
class SecondViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
}
#IBAction func CloseModal(_ sender: Any) {
self.dismiss(animated: true, completion: nil)
}
}
Don't forget to set the name of the ViewController in Storyboad;
from FirstViewController to SecondViewController
I have a view controller (containing my menu) presented on top of another view controller (my application).
I would need to access the presenting view controller (below my menu) from the presented view controller (my menu), for example to access some variables or make the presenting view controller perform one of its segues.
However, I just can't figure out how to do it.
I'm aware of the "presentingViewController" and "presentedViewController" variables but I didn't manage to use them successfully.
Any Idea ?
Code (from the presented VC, which as a reference to the AppDelegate in which the window is referenced) :
if let presentingViewController = self.appDelegate.window?.rootViewController?.presentingViewController {
presentingViewController.performSegue(withIdentifier: "nameOfMySegue", sender: self)
}
Here is a use of the delegation Design pattern to talk back to the presenting view controller.
First Declare a protocol, that list out all the variables and methods a delegate is expected to respond to.
protocol SomeProtocol {
var someVariable : String {get set}
func doSomething()
}
Next : Make your presenting view controller conform to the protocol.
Set your presenting VC as the delegate
class MainVC: UIViewController, SomeProtocol {
var someVariable: String = ""
func doSomething() {
// Implementation of do
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
// Your code goes here.
if let destVC = segue.destination as? SubVC{
destVC.delegate = self
}
}
}
Finally, when you are ready to call a method on the presenting VC (Delegate).
class SubVC: UIViewController {
var delegate : SomeProtocol?
func whenSomeEventHappens() {
// For eg : When a menu item is selected
// Set some Variable
delegate?.someVariable = "Some Value"
// Call a method on the deleate
delegate?.doSomething()
}
}
Assuming that VCApplication is presenting VCMenu, in VCMenu you can access VCApplication with:
weak let vcApplication = self.presentingViewController as? VCApplicationType
Your example self.appDelegate.window?.rootViewController?.presentingViewController is looking for the ViewController that presented the rootViewController - it will be nil.
EDIT
Per TheAppMentor I've added weak so there are no retain cycles.
I'm having the hardest time finding an answer for this.
I have a xib view that is within a scrollview that is within a view controller. In the xib I have a button with an action and I need to segue to a view controller I have in my storyboard. I also would like to be able to use a custom segue.
So far, I have read that I can instantiate the viewcontroller from the storyboard to segue to it. But then I don't know how to present that controller.
thanks for any help...
UPDATE:
this is the code I'm using to perform the segue.
In parent ViewController:
static var referenceVC: UIViewController?
override func viewDidLoad() {
super.viewDidLoad()
print("viewdidload")
LevelSelectViewController.referenceVC = self
setupScrollView()
}
code in xib view file
let vc = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "sightWordController")
let parent = LevelSelectViewController.referenceVC!
let segue = InFromRightCustomSegue(identifier: "test", source: parent, destination: vc)
segue.perform()
As noted in the comments, Segues are typically confined to storyboard usage as noted in the documentation. You can implement a custom xib view in a storyboard via #IBDesignable like approaches and have you're view load from the xib into the storyboard file/class. This way, you gain the benefits of both worlds. Otherwise, you may want to approach this in another fashion (such as delegates/target-action events, etc).
You may also climb the responder chain and call a segue related to the VC loaded from the storyboard (the segue doesn't necessarily have to be attached to any particular action) via getting a reference to the VC and calling the segue. You can climb the responder chain in a manner such as the example code below:
protocol ChildViewControllerContainer {
var parentViewController: UIViewController? { get }
}
protocol ViewControllerTraversable {
func viewController<T: UIViewController>() -> T?
}
extension UIView: ViewControllerTraversable {
func viewController<T: UIViewController>() -> T? {
var responder = next
while let currentResponder = responder {
guard responder is T else {
responder = currentResponder.next
continue
}
break
}
return responder as? T
}
}
extension UITableViewCell: ChildViewControllerContainer {
weak var parentViewController: UIViewController? {
return viewController() as UIViewController?
}
}
I have three main view controllers A, B, C, which are presented in the order by show segue. All the three view controllers are embedded in their own navigation controller. After dismissing a modal controller D presented on C, I would like to go back to controller A and reload data before it appears.
I referred to the solution from this question to unwind segue and wrote an action in controller A (I use AViewController to represent the class of controller A):
#IBAction func prepareForUnwindSegue(segue: UIStoryboardSegue?) {
if let destController = segue?.destinationViewController as? AViewController {
destController.reload()
}
}
override func canPerformUnwindSegueAction(action: Selector, fromViewController: UIViewController, withSender sender: AnyObject) -> Bool {
return self.respondsToSelector(action)
}
I dragged-exit between controller A and C by the above action, and name the unwind segue unwindToA. Then in the class of controller C, named CViewcontroller, I call the modal view D in one ActionSheet as follow:
let presentDAction = UIAlertAction(title: "Present D", style: .Default, handler: {(_) -> Void in
let controller: AnyObject? = self.storyboard!.instantiateViewControllerWithIdentifier("DView")
if let c = controller as? DViewController {
let navi = UINavigationController(rootViewController: c)
navi.modalPresentationStyle = UIModalPresentationStyle.FullScreen
// the following block wait and execute after view controller D dismissed
c.refreshAndUnwind = {[weak self](refresh) in
if let weakSelf = self {
if(refresh) {
weakSelf.performSegueWithIdentifier("unwindToA", sender: weakSelf)
}
}
}
}
})
The view controller did successfully unwind along with reloading data. However, it seems that the navigation bar remains still on controller C, and its title disappear. I have tried to drag-exit the navigation controller between A and C instead and modify the unwind segue action call to weakSelf.navidationController!.performSegueWithIdentifier("unwindToA", sender: weakSelf), but it doesn't work. Did I do anything wrong on my segue unwinding that cause this problem?
Sometimes using storyboard is not the best way to do things. I'd do this like this in your case:
var viewControllers = self.navigationController!.viewControllers
var controllerA = viewControllers[0] as! ControllerA
controllerA.reloadStuff()
var newViewControllers = [ controllerA ]
self.navigationController!.setViewControllers(newViewControllers, animated: true)
The code is much cleaner this way. You can set the navigationItem's title in viewDidAppear on each view if you have problems with it, you can be sure that it will be always called.
So the problem is simple: After I tried to modify my storyboard and remove those not-necessary navigation controllers, it performs just fine.
I have a main view controller that has been setup in Interface Builder to open a table view controller via popover segue connected to a button. I want to be able to dismiss the popover when an item inside of my popover table view is selected in didSelectRowAtIndexPath. In Objective-c I can just typecast the the segue in the prepareForSegue delegate to a UIStoryboardPopoverSegueand pass along its UIPopoverController to the table view controller. However, in Swift my downcast fails because it sees the segue as type UIStorybaordPopoverPresentationSegue (when stepping through with the debugger) which doesn't appear to be a public API.
Here's my code:
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject!) {
if segue.identifier == "ShowCollectionsSegue" {
if let collController:CollectionsTableViewController! = segue.destinationViewController as? CollectionsTableViewController {
if let popoverSegue = segue as? UIStoryboardPopoverSegue { // <-- This fails
collController.popover = popoverSegue.popoverController
}
}
}
}
How do I coerce the segue to a UIStoryboardPopoverSegue in order to access its popoverController property?
I'm open to solving the problem of dismissing the popover in response to a table view cell tap a different way, but it seems that when using a segue from the storyboard, the only way to dismiss the popover is by holding onto a reference to the popover controller somehow and the only way to do that as far as I can tell is to cast the segue to a popover segue which Swift doesn't want to let me do. Any ideas?
A strange problem, indeed. I noticed in the documentation, that UIStoryboardPopoverSegue does not inherit from any class. That explains why the cast does not work - UIStoryboardSegue is not its superclass. So I just tried to create a new object - it looks weird but works:
let popoverSegue = UIStoryboardPopoverSegue(
identifier: segue.identifier,
source: self,
destination: segue.destinationViewController as UIViewController)
println("Is there a controller? \(popoverSegue.popoverController.description)")
// YES !!
EDIT
But this controller will not dismiss the popover :(
The fix is to specify the segue in Interface Builder as "Deprecated Segues : Popover". Then the code would be as expected
let popoverSegue = segue as UIStoryboardPopoverSegue
if let destination = segue.destinationViewController as? TableViewController {
destination.delegate = self
self.popoverController = popoverSegue.popoverController
}