I would like to know if it is possible to assign two different unwind method at the same button. For example:
I have this views navigations:
Home->A->B
Home->C->B
A and C views navigates to B, but then I want to return to previous views using the same B view and controller.
It is possible?
I have been thinking about write assign unwind method to the button programmatically depending what view comes.
Thanks in advance
I'm sorry about my english, is not good.
Here's a Swift solution that worked well for me. The code below only works if you hookup your segues correctly in the storyboard and in code. Checkout this page for great explanations on setting up unwind segues.
In summary:
You're accessing the same view from multiple other views. So, when you segue to a view, you can pass the source view controller (the view that you're currently in) to a property in the view that you're going to.
In your view that you will unwind out of, you can check the property holding the info (the class) on where you came from, and then perform a segue based on what view it is.
The code: (using ex: Home -> A -> B or... Home -> C -> B)
Note: B is the view that will unwind to multiple different views.
In A or C: (code works the same way in both views)
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "segueIdentifierInViewAthatGoesToViewB" {
let controller:B = segue.destinationViewController as! B
//the code below passes our current view controller class to a property in view B.
//So, view B will know what view we came from.
//In our example, we're coming from view A or C
controller.viewControllerNavigatedFrom = segue.sourceViewController
}
}
In B:
//setup an IBAction that will check the source view controller (that we passed when we segued to this view) and perform a segue based on where we came from. You can hook this up to a button or anything you want really.
//isKindOfClass(A) - "A" would be the name of your class
//setup a property to receive the view controller class where we are coming from
var viewControllerNavigatedFrom:AnyObject?
#IBAction func myButtonPressed(sender: AnyObject) {
if self.viewControllerNavigatedFrom!.isKindOfClass(A) {
//Unwind to view A
performSegueWithIdentifier("unwindFromBbackToA", sender: sender)
}
else if self.viewControllerNavigatedFrom!.isKindOfClass(C) {
//Unwind to view C
performSegueWithIdentifier("unwindFromBbackToC", sender: sender)
}
}
Although, question isn't very clear. But what I could understand is that you want to navigate back to the previous view i.e. B>C or B>A depending upon where user came from.
If so, then check the UINavigationController. It keeps track of the navigation history and automatically adds a back button. Kind of like the back button in our browsers.
Here is a tutorial, although a bit old: Link
Related
I'm new with IOS and Swift so don't judge if solution is easy.
I have three ViewControllers like A,B and C.
I started from A -> NavigationController -> B -> NavigationController -> C
In specific situation I need to come back from C to A without seeing B. Is any way to do this?
Maybe changing the parent navigationController? Maybe I can print stack with every current view? - it will be really helpful.
I tried dismiss C and B view one by one and it work's but then we can see B view for a moment - so it's not a solution for me.
P.s : I'm using Modal kind to switch between controllers.
enter image description here
If A is always the first view controller, you can just do :
viewcontrollerC.navigationController?.popToRootViewController(animated: true)
This methods pop the stack to the first view controller, without displaying intermediates ones
If A is not the first viewController, you can do :
viewcontrollerC.navigationController?. popToViewController(viewControllerA, animated: true)
If you don't have a reference to viewControllerA, search it in the stack :
let viewControllerA: UIViewController?
for (let vc in (self.navigationController?.viewControllers ?? [])) {
//adust the test to find the appropriate controller
if vc.isKindOf(ViewControllerAClass.self) {
viewControllerA = vc
break
}
}
if let viewControllerA = viewControllerA {
self.navigationController?.popToViewController(viewControllerA, animated: true)
}
source : https://developer.apple.com/documentation/uikit/uinavigationcontroller/1621871-poptoviewcontroller
There are 2 ways you can achieve this. The simple to implement is in View Controller C you can, on in the specific situation, invoke following function:
navigationController?.popToRootViewController(animated: true)
This will pop all the navigational view hierarchy and take you back to the root i.e. the first view controller.
Second approach is to define unwind method in the view controller you want to go back to. In view controller when you start typing unwind, in Xcode 10 you will get autocomplete to add this Swift Unwind Segue Method.
#IBAction func unwindToA(_ unwindSegue: UIStoryboardSegue) {
let sourceViewController = unwindSegue.source
// Use data from the view controller which initiated the unwind segue
}
In this particular question let us say you added this method in View Controller A as you want to go back to it. I assume you have a button on View Controller C to go back to A. Controll+Drag from the button to the Exit symbol of the view controller A. The unwindToA method will automatically pop-up. Connect to it and you are done. When the user presses this button it will go back 2 navigation controllers to A.
Note: By this method you can go back to any navigation controller on the Navigation stack and it is not limited to root view controller alone. Below I am addition picture showing the exit on a view controller.
I am using prepare for segue to set a dictionary variable in another view controller. But the issue is the view controller opens the map without the data. How can I make sure I go to next view controller only after the dictionary variable data has been set.
Here is my code
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "showMapSegue"
{
if let mapVC = segue.destination as? MapVC
{
if vendorStoreKeys.count != 0{
mapVC.vendorStore = vendorStoreKeys
}
}
}
}
But the vendor store array in next view controller is still empty when the controller is visible. It sets the data after some time but at that point I am unable to reload that view controller so I need to make sure I don't go to next view controller before the mapVC.vendorStore variable is properly set.
I was able to resolve the issue. Prepare for should have set the data before calling and it was. Issue was I actually forgot to remove the segue in the storyboard which was directly going from the button to the new view controller. So here is what I did
Removed the segue which was going directly from the collection view cell button to the next story board
Created a new segue from the top of the view controller to the next view controller
Named that segue "showMapSegue"
Build and Run. I got the data successfully in the next view controller. Hope it helps.
I have three views, each with its own view controller: VC1, VC2, VC3.
The user will frequently switch back and forth between each of the three views, both forward and backward.
Each view contains data: both shared from the previous view and data unique to that view.
When the user goes back to a View that he has already visited, the data displayed on that view needs to be retained (the same data as he saw the last time he visited that view), and not set to the default values the first time he visited the view.
In the first view controller, VC1, I am using a prepare for segue to push data from VC1 to VC2 or VC3:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "segueToVC2” {
let destinationViewController: VC2 = segue.destination as! VC2;
destinationViewController.passedData1 = firstAmount
destinationViewController.passedData2 = secondAmount
destinationViewController.passedData3 = thirdAmount
} else {
let destinationViewController: VC3 = segue.destination as! VC3;
destinationViewController.passedData1 = firstAmount
destinationViewController.passedData2 = secondAmount
destinationViewController.passedData3 = thirdAmount
destinationViewController.passedData4 = fourthAmount
}
By tapping the GO BACK button on each view, I return to the previous view:
#IBAction func goBackButtonPressed(_ sender: Any) {
print("Back Button Pressed!")
self.view.window?.rootViewController?.dismiss(animated: true, completion: nil)
}
I am having trouble passing data backwards. And when I return to VC2 from VC1, data has been reset to 0. I have no segues going back from VC2 to VC1 or from VC3 to VC2. Would that be the cleanest way to pass the data back: to create another segue in Main.storyboard from VC2 to VC1 and then add another ‘if’ to my prepare for segue that checks for VC1?
I am passing ALL these variables back and forth between view controllers but only using some of them in each view controller. It seems like a waste and I don't think I am on the right track here.
Any help or suggestions?
View controllers should never store data. They are responsible for coordinating between model objects and view objects. That's their whole point. The pattern you're looking for is called MVC (Model-View-Controller) and it's a core part of iOS development.
Move your data out of the view controllers and put it into model classes. Each view controller should fetch data out of the model, and send updates into the model. The only thing the view controllers should pass between themselves is what model objects to work on, and most of the time that only needs to pass in one direction (down the stack).
Delegation can be a useful tool here, and you can also investigate "unwind segues" which are built to help you send data upstream. But again, the data you should be sending is mostly references to the model, and the model itself needs to live outside the view controllers.
It's in Objective-C, but still one of the best simple examples from Apple on MVC design is TheElements, and is worth exploring as a basis. Even without reading the Objective-C, you can see how the various pieces fit together.
I haven't studied it as much as TheElements, but Lister claims to be a good demonstration of MVC patterns in Swift using modern iOS techniques.
Why don't you call a delegate which passes the data to the view controller when you press back button.
Or if the data shared by all view controllers reflect the same value. Make a singleton class and use those values across the app.
example singleton class:
class SomeModel {
static let shared = SomeModel()
private init() {}
}
I have a view controller with 2 labels - each to be populated from lists in 2 separate table controllers. In my view controller I have 2 variables (temp and temp_1) to receive the data from the table controllers and populate the labels.
When I call the first table view and select an item that works fine and my first label is populated, when I then call the second table view that works too and my second label is populated - except that the first label is now blank - because temp is now blank.
I have attached my prepareForSegue from my first table view showing me passing my variable temp back to my view controller. (My second is similar and passes back temp_1)
Thanks for any help.
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "return_1" {
if let destination = segue.destinationViewController as? main_ViewController {
if let row = tableView.indexPathForSelectedRow?.row {
destination.temp = array1[row] as! String
}
}
}
}
My guess is that what you are saying in words is not what in fact you are actually doing. You say "back to my view controller", as if you were returning from the table view to the main view controller. That is what you want to do and what you should do, but it isn't what you're doing (I'm guessing). I think you've set up your storyboard with a normal segue from the table view to the main view controller. That doesn't go back; it makes a whole new main view controller. So of course the old label value is missing, because this is a different view controller from the one with the old label value (which effectively is still there, two layers down, covered up by this new instance).
What you want is an unwind segue. That is how you say "go back" in a storyboard.
I am using a UICollectionView to show a list of images.
1)By clicking on any cell the image and some description about it is displayed in the resulting view controller(using a push segue).
2)When i swipe from the left/right edge(using PanGesture) i need to display the details of the previous/next image in the collection view.
3)But the back button of the navigation bar has to take me back to the collection view and not to the previous displayed details (shown by the PanGesture).
I know how to get 1 and 2 done but don't have a concrete idea to get the 3rd job done.
Any help would be appreciated.
You can find your desired UIViewController in your navigation stack using for loop. Try this. This is in Swift
for (var i = 0; i < self.navigationController?.viewControllers.count; i++) {
if (self.navigationController?.viewControllers[i].isKindOfClass(YourViewController) == true) {
println("is sw \(self.navigationController!.viewControllers[i])")
(self.navigationController!.viewControllers[i] as! YourViewController)
self.navigationController?.popToViewController(self.navigationController!.viewControllers[i] as! YourViewController, animated: true)
break;
}
When you navigate from one view to another (e.g. by showing a detail view of your images one after the other, then all these views are internally piled up as a stack.
Thus, if you want to jump directly to a view somewhere in between this stack (e.g. the collection view), then you can use the Unwind Segue.
In your case it should work like this:
First, in your collection view (i.e. your back button destination) you need to implement a UIStoryboard Segue as follows
#IBAction func myGoBackPoint(segue: UIStoryboardSegue) {
println("Jump directly back here from any other view")
}
Then, in the storyboard of your detail view you ctrl-drag directly to top rightmost Exit marker and choose the previously created back button destination:
In the code of the detail view implement the "go back instruction"
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "My Unwind Segue" {
if let myUnwindSegue = segue.destinationViewController as? MyCollectionViewController {
// prepare for segue
}
}
}
Hope this helps.
Finally after researching a lot i found that using a collection view with each cell taking up the whole screen is the best way to go about solving this issue.
Thankyou