I have two classes:
class ExplorerViewController: UIViewController {
lazy var studyButton: ExploreButton = {
let button = ExploreButton()
button.setTitle("Study", forState: .Normal)
return button
}()
}
and
class ViewController: UIViewController, UISearchBarDelegate, LocateOnTheMap, GMSMapViewDelegate {
}
I'm trying to make it so that when I click the studyButton, it sends the button title to ViewController and goes to that view.
I'm not using storyboards and am having trouble with segues since every tutorial seems to give different examples that are specific to the things they've been working with and 95% of them seem to be operating with storyboard. Can someone give me a general way of how to do this?
How do I give the starting view controller an identifier because it isn't instantiated like the other controllers that I 'move' to after. How can I move from ViewController to ExplorerViewController and then move back to that same ViewController (with all changes intact).
Create an initializer for your ViewController that receives the "title" variable:
class ViewController: UIViewController, UISearchBarDelegate, LocateOnTheMap, GMSMapViewDelegate {
var btnTitle: String?
init(nibName nibNameOrNil: String?, bundle nibBundleOrNil: NSBundle?, btnTitle:String?) {
super.init(nibName: nibNameOrNil, bundle: nibBundleOrNil)
self.btnTitle = btnTitle
}
}
When creating the ViewController object use this initializer.
var viewController = ViewController(nibName: "ViewController", bundle: nil, btnTitle: title
You can initialize UIViewController that you want navigate to, assign data to properties in that controller and call this method:
presentViewController(viewController, animated: true, completion: nil)
For example:
let destinationViewController = ViewController()
destinationViewController.frame = self.view.frame
destinationViewController.buttonTitle = "title"
self.presentViewController(destinationViewController, animated: true, completion: nil)
Although I would suggest you to get familiar with Storyboards and perform navigation with Segues.
Make sure of two things:-
1.) You have given your viewController an StoryBoard ID lets say "viewControllerVC_ID" in it's Identity inspector
2.) You have NavigationController Embed in to your Initial entry point View Controller
In ViewController declare a variable
var btnLabelTxt : String!
Create an #IBAction of that button in ExplorerViewController :-
#IBAction func exploreBtnAction(sender : UIButton!){
let vcScene = self.navigationController?.storyboard?.instantiateViewControllerWithIdentifier("viewControllerVC_ID") as! ViewController
vcScene.btnLabelTxt = "Study"
//or you can just access the button itself in the viewController and set the title
//By vcScene.yourBtn.setTitle("Study", forState: .Normal)
self.navigationController?.pushViewController(vcScene, animated: true)
}
please see this question How to push viewcontroller ( view controller )? for how to switch between views.
to pass data once you have reference to the new view, you can assign the data to a property of that view.
Related
I'll give an example of what I want so it's not so confusing:
Example:
Let's say that I have a map that adds every time that my user scrolls 3 annotations dynamically. Now I have a button under the map and when I press it I go to another viewController do what I want and get back to the viewController with the map, now I want to find all the annotations that my map had and not reload the view at all.
I used to use this function that I made to move between viewControllers:
func move(identifier: String , viewController : UIViewController) -> Void {
let mstoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
let vc: UIViewController = mstoryboard.instantiateViewControllerWithIdentifier(identifier)
viewController.presentViewController(vc, animated: true, completion: nil)
}
I also tried this:
let vc = self.storyboard?.instantiateViewControllerWithIdentifier("view") as? MyViewcontroller
self.presentViewController(vc!, animated: true, completion: nil)
These two when I use them the viewcontroller that appears is calling viewDidload so its like it appeared for the first time.
Another example is the tabBarViewController if you notice when you navigate through tabs nothing reloads (only function that is called is viewDidAppear )
EDIT
test file
The problem is caused by the fact that the map controller gets deallocated when navigating back to the other controller, and another one is created when you want to move again to the map screen.
What you need is to hold on onto the same controller instance, and present that one. Keeping a strong reference in the presenting controller would suffice.
class PresentingController {
// making the property lazy will result in the getter code
// being executed only when asked the first time
lazy var mapController = { () -> UIViewController in
let mstoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
return mstoryboard.instantiateViewControllerWithIdentifier("mapControllerIdentifier")
}()
func moveToMap() {
// simply use the mapController property
// the property reference will make sure the controller won't
// get deallocated, so every time you navigate to that screen
// you'll get the same controller
presentViewController(mapController, animated: true, completion: nil)
}
}
According to the same project you posted, you instantiate a new UIViewController when going from view 2 back to view 1 and that is why your viewDidLoad gets called again and your entire map view is reloaded.
In your sample project, instead of
lazy var mapController2 = { () -> UIViewController in
let mstoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
return mstoryboard.instantiateViewController(withIdentifier: "first")
}
You should just dismiss your view 2 on the button press.
#IBAction func butto(_ sender: AnyObject) {
//Your initial code
//PresentingController().moveToMap(self, flag: 1)
self.dismiss(animated: true, completion: nil)
}
When you present a new UIViewController, the older UIViewController is not removed from memory, it is just hidden behind the new UIViewController. So whenever you wish to go back to a UIViewController with the previous state maintained, all you need to do is close the new UIViewController
However, if you are doing some tasks that you performed on your second UIViewController that you wish to be reflected in your initial UIViewController, you will have to setup closures to update your initial UIViewController.
I'm building an app (in XCode 8.2.1) where some objects are displayed on a 2D board, and when the user taps one of these objects some info should be displayed about it as a styled modal info box. My design is to have the info written in a separate view controller, which I would display when needed.
I've designed a basic stub for the second view controller and added a single label to it in the interface builder. Then I've ctrl-linked this label to my custom VC class:
class InfoViewController: UIViewController {
#IBOutlet weak var info: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
}
func displayInfo() {
info.attributedText = NSAttributedString(string: "abc")
}
}
However, when I test my app and tap the object, the info field is nil even in the viewDidLoad() method of my custom VC class. The way I'm displaying my VC is as follows:
let infoViewController = InfoViewController()
infoViewController.modalPresentationStyle = .overCurrentContext
self.present(infoViewController, animated: true, completion: nil)
infoViewController.displayInfo()
(Note: In the end I will have only one single instance of InfoViewController but this is just for testing. I don't expect having a global instance would make any difference?)
As I said, be it inside the viewDidLoad() method or in the displayInfo() method, info is always nil, such that setting its attributedString attribute crashes the app. Thinking the present method might be called asynchronously, I've tried calling displayInfo() from inside viewDidLoad(), but that didn't make any difference.
Can anyone tell my what I've forgotten that would allow my IBOutlet from being properly initialized properly?
Thanks!
David
The problem is the reference to InfoViewController(), which instantiates the view controller independent of any storyboard scene. You want to use instantiateViewController:
let infoViewController = storyboard?.instantiateViewController(withIdentifier: "Info") as! InfoViewController
infoViewController.modalPresentationStyle = .overCurrentContext
present(infoViewController, animated: true) {
infoViewController.displayInfo()
}
A couple of notes:
This assumes that (a) you've given the scene in the storyboard a "storyboard id"; (b) you've set the base class for that scene to InfoViewController.
Note, I called displayInfo in the completion handler of present because you probably don't want that called until the scene has been presented and the outlets have been hooked up.
Alternatively, you can update non-outlet properties of the InfoViewController immediately after instantiating it and then have its viewDidLoad take those properties and update the outlets, e.g.:
class InfoViewController: UIViewController {
var info: String!
#IBOutlet weak var infoLabel: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
infoLabel.attributedText = NSAttributedString(string: info)
}
}
Note, I changed the #IBOutlet name to be infoLabel and added the String property called info. That tends to be the convention, that outlets bear some suffix indicating the type of control, and model objects, like the String property, are without the suffix. (You'll just want to make sure you remove that old outlet in the connections inspector in IB so that you don't have problems with these property name changes.)
Anyway, you can then do:
let infoViewController = storyboard?.instantiateViewController(withIdentifier: "Info") as! InfoViewController
infoViewController.info = "abc"
infoViewController.modalPresentationStyle = .overCurrentContext
present(infoViewController, animated: true, completion: nil)
The key point is don't try to update outlets of the scene immediately after instantiating it, but make sure that this is deferred until after viewDidLoad was called.
I Replaced
let vc = CCDetailViewController()
With
let vc = self.storyboard?.instantiateViewController(withIdentifier: "CCDetailViewController")
Finally
self.present(vc!, animated: true, completion: nil)
Now It Works...
In my case, I had created new view controller for the same class. Which had ended up with two view controllers in storyboard, but referring to the same class. After deleting old view controller, everything worked fine.
Hope it helps to someone.
Suppose I have three view controllers in a Main.storyboard. Two of the three, vc_login and vc_studyDesc load the other view controller using a UIButton with 'present modally' option.
The other one vc_signup has a UIButton, which may go back to the previous controller. To implement this, I used the following methods:
vc_studyDesc has an identifier of studyDesc; I let it pass its identifier to vc_signup. In the same way, vc_login has login as an identifier.
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if sender as! UIButton == qnaSignUp {
let signup = segue.destinationViewController as! vc_signup
signup.latestVC = "studyDesc"}}
This one is in the UIViewController class for vc_signup. By referencing a string latestVC, the method determines which VC to move on.
#IBAction func backBtnClick(sender: UIButton) {
print("latestVS: \(latestVC)")
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let vc = storyboard.instantiateViewControllerWithIdentifier(latestVC)
vc.modalTransitionStyle = UIModalTransitionStyle.CrossDissolve
print("check check")
self.presentViewController(vc, animated: true, completion: nil)}
The problem I have is that the app gets terminated when vc_studyDesc is called by vc_signup. I found that this is because I missed a significant variable which must be loaded in vc_signup.
vc_studyDesc has some data to be referenced from Firebase when it is loaded. I did this by loading a variable postID from the prior vc to vc_studyDesc; which is vc_list.
So I just saved postID using NSUserdefaults.standardUserDefaults(). It is solved but I'm wondering if there's any way to pass data using the way I used in vc_signup.
As far as I see, I cannot find any way to pass the data into vc_studyDesc.swift; for the vc is chosen by its identifier..
Can I pass the variable I want in the way I want?? And adding tags would be appreciated!
So there are a couple problems with this design.
When you instantiate a viewController you are creating a new instance of that class, and presenting it adds it to the stack. Think of the stack like a deck of cards, you start with one card and then add or remove them, the top card being the visible vc. When you are going back to studyDesc you are instantiating and presenting it so you will have 3 VCs in your stack, of which two are studyDesc (the one you started with and the one you add when you try to go back)
To remove a VC from the stack you can use
dismissViewController(animated: true, completion: nil)
or if you have the VCs in a navigation controller you can use
popViewControllerController(animated: true, completion: nil)
in terms of passing information between viewControllers, if the info is in the VC you use to present your new controller you can use prepareForSegue like you already have. To pass information back you should use a delegate pattern. So to implement a delegate pattern in this case you would do the following:
Declare a protocol (not inside your classes, above there but below your import's)
protocol SignUpDelegate {
signInCompleted(infoToPass: AnyObject)
}
Then have your studyDesc class conform to this protocol and implement the function signInCompleted
StudyDescVC: UIViewController, SignUpDelegate {
func signInCompleted(infoToPass: AnyObject) {
// do what you want with the info here
}
}
Then in your signUpVc add a var delegate (which will be used to call the signInCompeleted function)
class SignInVC: UIViewController {
var delegate: SignUpDelegate!
func finishedSigningIn() {
delegate.signInCompleted(infoToPass: //yourinfo)
self.dismissViewControllerAnimated(true, completion: nil)
}
And then in your prepareForSegue set the delegate
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if sender as! UIButton == qnaSignUp {
let signup = segue.destinationViewController as! vc_signup
signup.delegate = self
}
}
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let vc = storyboard.instantiateViewControllerWithIdentifier(latestVC) as! YOUR_VIEW_CONTROLLER_NAME
vc.modalTransitionStyle = UIModalTransitionStyle.CrossDissolve
vc.name = "Andrew"
print("check check")
self.presentViewController(vc, animated: true, completion: nil)
//set a variale or property to your viewController
class YOUR_VIEW_CONTROLLER_NAME: UIViewController {
var name: String?
}
On my iPad app, I have a UIViewController with a button that open a modalView.
#IBAction func showPostCommentViewController(sender: AnyObject){
let modalView = UIStoryboard(name: "Main", bundle: nil).instantiateViewControllerWithIdentifier("PostCommentViewController") as! PostCommentViewController
modalView.modalTransitionStyle = UIModalTransitionStyle.CoverVertical
modalView.modalPresentationStyle = UIModalPresentationStyle.FormSheet
modalView.delegate=self
self.presentViewController(modalView, animated: true, completion: nil)
}
When I close the modalView with dismissViewControllerAnimated, I would like "refresh" my view controller (because I added new content). But as the modal view is a "formsheet" style, viewDidAppear or viewWillAppear aren't called.
I tried to use setNeedsDisplay, but it doesn't work.
I don't know how to do.
This would be a perfect use case for the delegate pattern.
1) define a protocol within PostCommentViewController.
protocol PostCommentVCInformationDelegate {
func hasDismissedPostCommentViewController(controller:PostCommentViewController)
}
2) Set a delegate variable within PostCommentViewController
var delegate: PostCommentVCInformationDelegate?
3) When you dismiss PostCommentViewController, you will call delegate?.hasDismissedPostCommentViewController(self)
This will send information back to the presenting VC.
4) Now we have our presenting View Controller conform to this protocol.
class ViewController: UIViewController, PostCommentVCInformationDelegate
5) When presenting the modal View:
modalView.delegate = self
6) Finally, we implement:
func hasDismissedPostCommentViewController(controller: PostCommentViewController) {
//Update
}
I'm trying to add a navigation controller to my UIViewController subclass programmatically (I'm not using storyboards) and I wanted to find the best place to init it and configure such.
I have tried viewDidLoad (the views weren't initialized by init) and a convenience init (just to make sure) method but no luck.
Here's how I'm creating it:
override init!(nibName nibNameOrNil: String!, bundle nibBundleOrNil: NSBundle!) {
super.init(nibName: nibNameOrNil, bundle: nibBundleOrNil)
let nav = UINavigationController(rootViewController: self)
}
What would be the most appropriate method to place this logic in? I would like to keep this logic contained within this VC.
I am able to accomplish this by creating the nav. with a root vc from the presenting VC, but this leaks this logic and I'd rather not do that.
I'm not sure this is what you're looking for, but you could put some logic within a method in the controller you're presenting to determine whether it should be presented with or without a navigation controller; doing it this way means the presenting view controller doesn't need to know whether the controller it's presenting is embedded in a navigation controller or not. The presenting controller, would call this method after instantiating your controller. The presented controller could look something like this,
class NextViewController: UIViewController {
var wantsNavigationcontroller = true
func viewControllerWithOrWithoutNavigationController() -> UIViewController {
if wantsNavigationcontroller {
let nav = UINavigationController(rootViewController: self)
return nav
}else{
return self
}
}
}
The presenting controller would do this,
#IBAction func PresentNextcontroller(sender: UIButton) {
var nextVC = NextViewController()
self.presentViewController(nextVC.viewControllerWithOrWithoutNavigationController(), animated: true, completion: nil)
}