How can I access a title inside the navigation controller from a separate Class? I embedded my mainVC into the navigation controller via Storyboard. I can access the title from inside the viewDidLoad from inside the same Class like this self.navigationItem.title = "MyTitle". However, I need to access the title from a separate class 'CustomNavigation like this:
class: CustomNavigation: UIViewController() {
override func viewDidLoad(){
super.viewDidLoad()
func createCustomNav(){
self.navigationItem.title = "MyTitle"
}
}
}
Unfortunately it doesn't work. I also tried this:
func createCustomNav(){
let nav = UINavigationBar()
let title = UINavigationItem(title: "MyTitle")
nav.setItems([title], animated: false)
self.view.addSubview(nav)
}
This does't work neither. I don't get any errors.
I instantiate CustomNavigation inside the mainVC: var customNavigation = CustomNavigation()
Any help would be greatly appreciate it!
Set up a protocol that describes the work you want done.
protocol NavigationTitler {
func updateTitle(with title: String)
}
Define how your class will use the protocol.
class CustomNavigation: UINavigationController {
var titleDelegate: NavigationTitler?
func work() {
if let del = titleDelegate {
del.updateTitle(with: "Title from other object")
}
}
}
Implement the protocol (this is for your mainVC).
class ViewController: UIViewController, NavigationTitler {
var customNavigation: CustomNavigation?
func updateTitle(with title: String) {
self.navigationItem.title = title
}
func buildCustomController() {
customNavigation = CustomNavigation()
customNavigation!.titleDelegate = self
}
}
Get the title from a UITabBarItem, use as title in current VC:
//Titel einstellen
let x = navigationController?.tabBarItem.title ?? ""
self.title = x //titel in VC
Related
I am trying to use MVVM. I am going to VC2 from VC1. I am updating the viewModel.fromVC = 1, but the value is not updating in the VC2.
Here is what I mean:
There is a viewModel, in it there is a var fromVC = Int(). Now, in vc1, I am calling the viewModel as
let viewModel = viewModel().
Now, on the tap of button, I am updating the viewModel.fromVC = 8. And, moving to the next screen. In the next screen, when I print fromVC then I get the value as 0 instead of 8.
This is how the VC2 looks like
class VC2 {
let viewModel = viewModel()
func abc() {
print(viewModel.fromVC)
}
}
Now, I am calling abc() in viewDidLoad and the fromVC is printed as 0 instead of 8. Any help?
For the MVVM pattern you need to understand that it's a layer split in 2 different parts: Inputs & Outputs.
Int terms of inputs, your viewModel needs to catch every event from the viewController, and for the Outputs, this is the way were the viewModel will send data (correctly formatted) to the viewController.
So basically, if we have a viewController like this:
final class HomeViewController: UIViewController {
// MARK: - Outlets
#IBOutlet private weak var titleLabel: UILabel!
// MARK: - View life cycle
override func viewDidLoad() {
super.viewDidLoad()
}
// MARK: - Actions
#IBAction func buttonTouchUp(_ sender: Any) {
titleLabel.text = "toto"
}
}
We need to extract the responsibilities to a viewModel, since the viewController is handling the touchUp event, and owning the data to bring to th label.
By Extracting this, you will keep the responsibility correctly decided and after all, you'll be able to test your viewModel correctly 🙌
So how to do it? Easy, let's take a look to our futur viewModel:
final class HomeViewModel {
// MARK: - Private properties
private let title: String
// MARK: - Initializer
init(title: String) {
self.title = title
}
// MARK: - Outputs
var titleText: ((String) -> Void)?
// MARK: - Inputs
func viewDidLoad() {
titleText?("")
}
func buttonDidPress() {
titleText?(title)
}
}
So now, by doing this, you are keeping safe the different responsibilities, let's see how to bind our viewModel to our previous viewController :
final class HomeViewController: UIViewController {
// MARK: - public var
var viewModel: HomeViewModel!
// MARK: - Outlets
#IBOutlet private weak var titleLabel: UILabel!
// MARK: - View life cycle
override func viewDidLoad() {
super.viewDidLoad()
bind(to: viewModel)
viewModel.viewDidLoad()
}
// MARK: - Private func
private func bind(to viewModel: HomeViewModel) {
viewModel.titleText = { [weak self] title in
self?.titleLabel.text = title
}
}
// MARK: - Actions
#IBAction func buttonTouchUp(_ sender: Any) {
viewModel.buttonDidPress()
}
}
So one thing is missing, you'll asking me "but how to initialise our viewModel inside the viewController?"
Basically you should once again extract responsibilities, you could have a Screens layer which would have the responsibility to create the view like this:
final class Screens {
// MARK: - Properties
private let storyboard = UIStoryboard(name: StoryboardName, bundle: Bundle(for: Screens.self))
// MARK: - Home View Controller
func createHomeViewController(with title: String) -> HomeViewController {
let viewModel = HomeViewModel(title: title)
let viewController = storyboard.instantiateViewController(withIdentifier: "Home") as! HomeViewController
viewController.viewModel = viewModel
return viewController
}
}
And finally do something like this:
let screens = Screens()
let homeViewController = screens.createHomeViewController(with: "Toto")
But the main subject was to bring the possibility to test it correctly, so how to do it? very easy!
import XCTest
#testable import mvvmApp
final class HomeViewModelTests: XCTestCase {
func testGivenAHomeViewModel_WhenViewDidLoad_titleLabelTextIsEmpty() {
let viewModel = HomeViewModel(title: "toto")
let expectation = self.expectation("Returned title")
viewModel.titleText = { title in
XCTAssertEqual(title, "")
expectation.fulfill()
}
viewModel.viewDidLoad()
waitForExpectations(timeout: 1.0, handler: nil)
}
func testGivenAHomeViewModel_WhenButtonDidPress_titleLabelTextIsCorrectlyReturned() {
let viewModel = HomeViewModel(title: "toto")
let expectation = self.expectation("Returned title")
var counter = 0
viewModel.titleText = { title in
if counter == 1 {
XCTAssertEqual(title, "toto")
expectation.fulfill()
}
counter += 1
}
viewModel.viewDidLoad()
viewModel.buttonDidPress()
waitForExpectations(timeout: 1.0, handler: nil)
}
}
And that's it 💪
I am trying to notify ChatViewController that a chat was deleted in MessagesViewController using a protocol, but the delegate method implemented in ChatViewController is never called.
In the navigationController hierarchy ChatViewController is on top of MessagesViewController.
protocol MessagesViewControllerDelegate:class {
func chatWasDeletedFromDatabase(chatUID: String)
}
class MessagesViewController: UITableViewController {
weak var delegate: MessagesViewControllerDelegate?
func observeChatRemoved() {
print("it is gonna be called")
//inform ChatViewController that a chat was deleted.
self.delegate?.chatWasDeletedFromDatabase(chatUID: chat.chatUID)
print("was called here") //prints as expected
}
}
class ChatViewController: JSQMessagesViewController {
var messagesVC: MessagesViewController?
override func viewDidLoad() {
super.viewDidLoad()
messagesVC = storyboard?.instantiateViewController(withIdentifier: "MessagesViewController") as! MessagesViewController
messagesVC?.delegate = self
}
}
extension ChatViewController: MessagesViewControllerDelegate {
func chatWasDeletedFromDatabase(chatUID: String) {
print("chatWasDeletedFromDatabase called") //never prints out
if self.chatSelected.chatUID == chatUID {
//popToRootViewController
}
}
It seems
weak var delegate: MessagesViewControllerDelegate?
is nil you have to set it to the ChatViewController presented instance what ever how you present it
let chat = ///
self.delegate = chat
self.navigationController?.pushViewController(chat,animated:true)
Also do
chat.messagesVC = self
as this
messagesVC = storyboard?.instantiateViewController(withIdentifier: "MessagesViewController") as! MessagesViewController
messagesVC?.delegate = self
isn't the currently presented messagesVC , so comment the above 2 lines
I have this function in a helper class. It's to show/hide some stuff.
func showHideDetails(controller: UIViewController, isHidden: Bool) {
...
if controller is AddNewViewController {
let addNewViewController = controller as! AddNewViewController
addNewViewController.bgButton.isHidden = isHidden
} else if controller is EditViewController {
let editViewController = controller as! EditViewController
editViewController.bgButton.isHidden = isHidden
}
...
}
Is there is a way around to have one if statement, instead of one if statement for each controller? Something like,
if controller.hasProperty(bgButton) {
controller.bgButton.isHidden = isHidden
}
Thanks
You still need to cast using as? ..., however in order not to do that for all view controllers that have the bgButton, you can define a base protocol enforcing all classes conforming to it to have the bgButton:
public protocol Buttoned {
var bgButton: UIButton { get set }
func setHideButton(_ isHidden: Bool)
}
extension Buttoned {
public func setHideButton(_ isHidden: Bool) {
bgButton.isHidden = isHidden
}
}
public class AddNewViewController: Buttoned {
#IBOutlet fileprivate weak var bgButton: UIButton!
....
}
public class EditViewController: Buttoned {
#IBOutlet fileprivate weak var bgButton: UIButton!
....
}
then you can handle the action in the actual view controller like below:
func showHideDetails(controller: UIViewController, isHidden: Bool) {
...
if let controller = controller as? Buttoned {
controller.setHideButton(isHidden)
}
...
}
In the given scenario to replace your all if with single if means that you should have a common base class or your class conform to same protocol. However type cast still requires. You can use below code to achieve your desired functionality.
Create a protocol BackgroundButton
public protocol BackgroundButton {
var bgButton: UIButton { get }
}
Conforms all your custom UIViewController with this protocol in Extension like below
extension AddNewViewController : BackgroundButton {
var bgButton : UIButton {
return yourbutton // Use any instance of UIButton from your AddNewViewController
}
}
extension EditViewController : BackgroundButton {
var bgButton : UIButton {
return yourbutton // Use any instance of UIButton from your EditViewController
}
}
Finally update your method like this
func showHideDetails(controller: UIViewController, isHidden: Bool) {
...
if let controller = controller as? BackgroundButton {
controller.bgButton.isHidden = isHidden
controller.bgButton. //Do any thing which you want with your button
}
...
}
Hope this will help you to reduce your numbers of if
By using the delegation protocol I have tried to pass a string (inputFromUser.string) from NSViewController - mainController to custom subclass of NSView of NSPopover - PlasmidMapView, to drawRect function, see code below. But, it didn’t work. I don’t know where a mistake is. Maybe there is another way to pass this string.
Update
File 1.
protocol PlasmidMapDelegate {
func giveDataForPLasmidMap(dna: String)
}
class MainController: NSViewController {
#IBOutlet var inputFromUser: NSTextView!
var delegate: plasmidMapDelegate?
#IBAction func actionPopoverPlasmidMap(sender: AnyObject) {
popoverPlasmidMap.showRelativeToRect(sender.bounds,
ofView: sender as! NSView, preferredEdge: NSRectEdge.MinY)
let dna = inputDnaFromUser.string
delegate?.giveDataForPLasmidMap(dna!)
}
}
File 2
class PlasmidMapView: NSView, PlasmidMapDelegate {
var dnaForMap = String()
func giveDataForPLasmidMap(dna: String) {
dnaForMap = dna
}
override func drawRect(dirtyRect: NSRect) {
let objectOfMainController = MainController()
objectOfMainController.delegate = self
//here I have checked if the string dnaForMap is passed
let lengthOfString = CGFloat(dnaForMap.characters.count / 10)
let pathRect = NSInsetRect(self.bounds, 10, 45)
let path = NSBezierPath(roundedRect: pathRect,
xRadius: 5, yRadius: 5)
path.lineWidth = lengthOfString //the thickness of the line should vary in dependence on the number of typed letter in the NSTextView window - inputDnaFromUser
NSColor.lightGrayColor().setStroke()
path.stroke()
}
}
Ok, there's some architecture mistakes. You don't need delegate method and protocol at all. All you just need is well defined setter method:
I. Place your PlasmidMapView into NSViewController-subclass. This view controller must be set as contentViewController-property of your NSPopover-control. Don't forget to set it the way you need in viewDidLoad-method or another.
class PlasmidMapController : NSViewController {
weak var mapView: PlacmidMapView!
}
II. In your PlacmidMapView don't forget to call needsDisplay-method on dna did set:
class PlasmidMapView: NSView {
//...
var dnaForMap = String() {
didSet {
needsDisplay()
}
//...
}
III. Set dna-string whenever you need from your MainController-class.
#IBAction func actionPopoverPlasmidMap(sender: AnyObject) {
popoverPlasmidMap.showRelativeToRect(sender.bounds,
ofView: sender as! NSView, preferredEdge: NSRectEdge.MinY)
let dna = inputDnaFromUser.string
if let controller = popoverPlasmidMap.contentViewController as? PlasmidMapController {
controller.mapView.dna = dna
} else {
fatalError("Invalid popover content view controller")
}
}
In order to use delegation your class PlasmidMapView needs to have an instance of the MainController (btw name convention is Class, not class) and conform to the PlasmidMapDelegate (once again name convention dictates that it should be PlasmidMapDelegate). With that instance you then can:
mainController.delegate = self
So, after several days I have found a solution without any protocols and delegation as Astoria has mentioned. All what I needed to do was to make #IBOutlet var plasmidMapIBOutlet: PlasmidMapView!for my custom NSView in MainController class and then to use it to set the value for the dnaForMap in #IBAction func actionPopoverPlasmidMap(sender: AnyObject).
class PlasmidMapView: NSView
{
var dnaForMap = String()
}
class MainController: NSViewController
{
#IBOutlet var inputFromUser: NSTextView!
#IBOutlet var plasmidMapIBOutlet: PlasmidMapView!
#IBAction func actionPopoverPlasmidMap(sender: AnyObject)
{
plasmidMapIBOutlet.dnaForMap = inputDnaFromUser.string!
popoverPlasmidMap.showRelativeToRect(sender.bounds,
ofView: sender as! NSView, preferredEdge: NSRectEdge.MinY)
}
}
I have a custom popup view that has a UIDatePicker. This, when changed, changes the date of the save time. I also want the label on the in the CustomCell to be updated if the date has changed. I have used a delegate protocol to update the table but I cannot get this protocol to transfer the information on save. Can you help? I think I have hooked up all the correct code in the viewController class. I have tried this answer but I cannot set the delegate in the target class and there isn't a segue A Swift example of Custom Views for Data Input (custom in-app keyboard)
protocol DatePopUpViewDelegate: class {
func pastDate(date: String) // date that is chosen in picker
func isPastDateSet(isSet: Bool) // has chosen new date
}
#IBDesignable class DatePopUpView: UIView {
var delegate: DatePopUpViewDelegate?
func loadViewFromNib() -> UIView {
let bundle = NSBundle(forClass: self.dynamicType)
let nib = UINib(nibName: "DatePopUp", bundle: bundle)
let view = nib.instantiateWithOwner(self, options: nil)[0] as! UIView
delegate?.isPastDateSet(false)
return view
}
// close popup
#IBAction func closeButtonDatePopUp(sender: AnyObject) {
if dateToSave != openTime {
if let dateToSave = dateToSave {
SaveData.changedSaveTime = dateToSave
delegate?.pastDate(dateToSave)
delegate?.isPastDateSet(true)
}
} else {
SaveData.changedSaveTime = ""
delegate?.isPastDateSet(false)
}
}
class SaveTableViewCell: UITableViewCell, DatePopUpViewDelegate {
var changeDateLabel: Bool = false
override func awakeFromNib() {
super.awakeFromNib()
// Initialization code
changeDateLabel = false
datePopUpViewControllert.delegate = self
}
// delegate functions
func pastDate(date: String) {
self.labelDate = date
print("del date \(date)")
}
func isPastDateSet(isSet: Bool) {
self.changeDateLabel = isSet
print("is set by delegate \(isSet)")
}