Here's what I'm trying to do:
I have 2 views, Settings and Main Screen.
I've coded a segue to occur when a button in Settings is pressed, taking the view to the Main Screen. The identifier is "reset".
I'm trying to have the Main Screen perform a series of actions if this segue is triggered, but I can't find the function or way to do this.
Any help on how to implement this? I'd like it to trigger when the segue occurs.
You can pass arguments to the main screen in the prepareForSegue function in the settings page. Then in your main screen you can put in checks in your viewWillAppear function to handle them as you see fit.
Example:
In Settings:
override func prepareForSegue(segue: UIStoryboardSegue!, sender: AnyObject!) {
if (segue.identifier == "reset") {
// pass data to next view
let viewController:ViewController = segue!.destinationViewController as MainViewController
viewController.settings = settings // where settings is what you want to pass
}
}
In Main Screen:
override func viewWillAppear(animated: Bool) {
super.viewWillAppear(animated)
if self.settings { // Do something }
}
If you're wanting something to happen when the segued view controller is triggered you can do it in a couple of places.
If you want the event to happen at the time the segue is fired, perform your code inside of prepareForSegue. There you can check the UIStoryboardSegue object's identifier field for "reset" and if true, call your logic.
If you want it to happen when the destination view controller loads or appears, do it inside of its viewDidLoad or viewDidAppear methods. In your case those methods would exist on the "Main Screen" view controller class.
Related
I have two view controllers, the first one has two buttons, signup and login, the second VC does the function of signup and login stuff (I wrote functions to switch between signup and login mode), is it possible to identify if user pressed login/signup button in the first VC so the right function will be called in the second VC when performing segue?
You have tell the second view controller what to do upon the first view controller selected option (signin or signup). I would assume that you could do this by simply declaring a flag and send it to the second view controller, for instance:
Declare a boolean variable in your second view controller (let's say shouldBehavesAsLogin) which means if selection is login it should be true:
// Controller that could represents signin or signup:
class SecondViewController: UIViewController {
//...
var shouldBehavesAsLogin = false
// ...
}
thus you could determine what is the value that should be assigned to it based on which button tapped, first view controller:
class FirstViewController: UIViewController {
// ...
private var isLoginTapped = false
#IBAction func signinTapped(sender: UIButton) {
isLoginTapped = true
}
#IBAction func signupTapped(sender: UIButton) {
// nothing to do here, isLoginTapped is false by default...
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "MySegue"{
if let nextViewController = segue.destination as? SecondViewController {
nextViewController.shouldBehavesAsLogin = isLoginTapped
}
}
}
// ...
}
Thus all you have to do is to check the value of shouldBehavesAsLogin whether is it true to let the controller behaves as login or false to do the opposite.
Additional Tip:
If the purpose of adding IBActions for each button is just navigating to the second view controller, I would suggest to let both of the buttons to have the same IBAction, but you should let the sender to be of type UIButton instead of Any, thus you could do -for instance-:
#IBAction func aButtonTapped(sender: UIButton) {
// do the default behvior for both signin and signup (navigate to the second controller)
// signinButton is the button you tap for navigating to second controller to behaves as signin
isLoginTapped = sender === signinButton ? true : false
}
This answer assumes there is only one segue between the two view controllers. If there is more than one, you can simply use the segue identifier in prepareForSegue.
I'd handle this by using the sender parameter on either -prepare(for segue:sender:) or -performSegue(withIdentifier:sender), depending on whether you are triggering the segue directly from the button or in code.
If the buttons are triggering the segue, you can test whether the sender params is one of the two buttons concerned, and perform appropriate setup on the destination VC. If the segue is being triggered in code in an IBAction method, you could either pass through the button reference from the IBActions sender parameter, or pass some other identifying object that your prepareForSegue method is able to deal with.
Bear in mind that the target VC's views will not have loaded when prepareForSegue is called, so you may need to set some state on the target VC (e.g. a login/signup enum property) which is then used to set up the VC appropriately when its -viewDidLoad is called.
I have this two controller liked by segue:
My problem is that:
when I tap on selected table view'cell in general I have to follow the segue and so go to other controller , but if a specific condition is true I have to show ad alert view and so I don't follow the segue and so don't go to those controller.
In this way when I tap on selected cell I go always on the other controller.
How do I solve this problem?
if you override this function segue wont continue if you return false, this gives you the oportunity to show a warning under certain conditions, after that you can performSegueWithIdentifier("segueidentifier", sender: self), and your good to go.
override func shouldPerformSegueWithIdentifier(identifier: String!, sender: AnyObject?) -> Bool {
if identifier == "segueidentifier" {
//show warning and perform segue with this identifier on the accept button listener.
return false
}
}
return true
}
You can add a segue from one controller to another without specifying exact view which triggers the segue. Then just check your condition in didSelectRow method and call performSegue method if you need to show new view controller:
if condition {
performSegue(withIdentifier: "MySegueIdentifier", sender: nil)
}
else {
//show ad here
}
To add a segue between controllers just drag with right mouse button from one controller to another and pick "Show".
Then select segue and add a string identifier for it:
Make sure you use the same string in the code when you call performSegue method.
Currently working on my first IOS application. I have a purchase button, on success this currently sets a test button on the same view controller to hidden. Code is as follows
Decleration
#IBOutlet weak var Test: UIButton!
hide button on successful purchase
Test.isHidden = true
Now this works on my Test button, which is sat in the PurchaseViewController,class is the MasterViewController.Swift. (Purchase button that initiates this method is also in the same view controller)
PlanViewController also has a button, and class is also linked to MasterViewController.Swift. This has a separate button that i wish to hide on success of the purchase button.
When I utilise the same code as above for the button, it crashes, is their a limitation on manipulating other view controllers while you are not in it? I would have thought this worked given that they both have the Masterviewcontroller.swift as the class
Thanks
Although sometimes possible, it's generally not a good idea to directly manipulate one view controller's view from another view controller, as you are trying to do. Here is how I would do what you are trying to do.
First, set a segue identifier between your two view controllers by clicking on the segue in the storyboard and going to the attributes inspector. I suggest goToMasterViewController
In both MasterViewController.swift and PurchaseViewController.swift declare a variable var buttonHidden = false
In PurchaseViewController.swift add the following code, which will be called just before your segue to MasterViewController is performed:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if(segue.identifier == "goToMasterViewController") {
let destinationController = segue.destination as! MasterViewController
destinationController.buttonHidden = buttonHidden
}
}
When you hide the button in PurchaseViewController, also set buttonHidden = true
And finally in MasterViewController.swift:
override func viewWillAppear(_ animated: Bool) {
testButton.isHidden = buttonHidden
}
I have a TableViewController and I would like to trigger a segue within its navigation bar. I created the segue in the storyboard to my new ViewController. However if I click the bar button item, the view does not appear.
Instead the bar button item becomes inactive (greyed out) and the app freezes. There is no error message and the app does also not crash. The prepareForSegue method in my TableViewController also gets called
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
print("prepare for segue called")
print("destination view controller = \(segue.destinationViewController.description)")
}
I did the following things:
created a custom view Controller class for the second screen (in my storyboard and as a .swift file). I assigned the respective ViewController in the storyboard to my custom view controller in the Identity inspector
created an IBAction for a click event on the button and triggered
the segue programatically. The result remains the same.
prepareForSegue is called. The destionationViewController is correct
but does not show up. I removed this IBAction afterwards.
My destination view controller looks like this
class EnterUserDataViewController : UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
print("EnterUserDataViewController viewDidLoad called")
}
}
viewDidLoad never gets called even though the right segue has been triggered.
Can someone please give me a hint on why this happens?
You wouldn't happen to have a rogue breakpoint set somewhere would you?
If I put a breakpoint somewhere in the view loading cycle it recreates the exact symptoms you are describing.
I have a registration view controller. In it I process the input provided by the user soon as he clicks on the register button. This button in the view is connected to an IBAction where I validate the input provided.
How is t possible to trigger the segue and pass the data within the IBAction (not override prepareforsegue) to the next view controller? If the validation fails it shouldn't attempt to execute segue but rather stay on same view to display validation errors.
Thanks for support. The question has been asked in different ways before surely but I wasn't able to find a good combine of segue in ibaction and passing data too.
You can create a segue from one view controller to another and can put a check in your button's IBAction, like this:
if (validationPasses)
{
self.performSegueWithIdentifier("segueIdentifier", sender: self)
}
And if you don't won't to override your prepareforsegue, you can pass the data using delegates.
However, by overriding prepareforsegue, you can pass data to your next view controller like this:
override func prepareForSegue(segue: UIStoryboardSegue!, sender: AnyObject!) {
if (segue.identifier == "segueIdentifier") {
// pass data to next view controller
let vc : NextViewController = segue!.destinationViewController as NextViewController
vc.someVariable = someValue
}
}
Here NextViewController is your next viewcontroller, change its name to your next view controller and in this view controller define variable to whom you want to pass value, in this case it is someVariable