H!
I using a tutorial learing swift and now I want to know if this is possible.
Or how to do this a better way.
AController.swift
protocol AControllerProtocol {
func updateGui()
}
class AController {
func doSomething(){
// here I get incomming data and other stuff
// then the gui in multiple views needs an update
self.delegate.updateGui()
}
var delegate: AControllerProtocol
init(delegate: AControllerProtocol) {
self.delegate = delegate
}
}
BViewController.swift
class BViewController: AController {
#IBOutlet var tableView: UITableView!
var acontroller : AController?
override func viewDidLoad() {
super.viewDidLoad()
acontroller = AController(delegate: self)
}
func updateGui() {
// dispatch_async(dispatch_get_main_queue(), {
self.tableView!.reloadData()
// works, it runs this method and this tables is inside this BViewController
// })
}
}
CViewController.swift
class CViewController: AController {
lazy var acontroller : AController = AController(delegate: self)
#IBOutlet weak var tracksTableView: UITableView!
func updateGui() {
// dispatch_async(dispatch_get_main_queue(), {
self.tracksTableView!.reloadData()
// din't run, this table is only in this CViewController
// it only did run BViewController updateGui()
// })
}
}
As you can see I have two views:
BViewController.swift
tableView
CViewController.swift
tracksTableView
AController get some data and then fires the delegate.
I thought it will run the delegate in both views, so it can work in multiple classes, but it don't.
It only runs inside the BViewController.swift
Then I thought, maybe this is not the correct way to do this, (pushing updates to other classes).
A simple other solution would be something like this ?
BViewController.swift
class BViewController: AController {
#IBOutlet var tableView: UITableView!
var acontroller : AController?
override func viewDidLoad() {
super.viewDidLoad()
acontroller = AController(delegate: self)
}
func updateGui() {
// dispatch_async(dispatch_get_main_queue(), {
self.tableView!.reloadData()
// get to know how to do this here
CViewController.tracksTableView!.reloadData()
// })
}
}
CViewController.swift
class CViewController {
#IBOutlet weak var tracksTableView: UITableView!
}
Greetings,
Martijn
Have a look at NotificationCenter.
A controller could fire a notification when data arrives and dispatch it to the NotificationCenter.
B and C view controller could listen for that notification and add an observer with NotificationCenter. Their handlers would be triggered when the notification is posted.
Related
Via a method or closure, perhaps?
I created a subclass view controller of my superclass/parent view controller and placed labels with placeholder text in that subclass view controller.
I want to set the labels' values to blank strings from the superclass/parent view controller, or, specifically, from an IBAction function that causes the subclass view controller to appear.
Here is the code, first from the parent class, then from the subclass...
'''
class ViewController: UIViewController {
#IBAction func leavingView(){
self.EntryViewController.entryDateLabel.text = ""
self.EntryViewController.entryLabel.text = ""
self.dismiss(animated: true, completion: nil)
}
'''
then from the subclass...
'''
class EntryViewController: ViewController {
#IBOutlet var entryDateLabel: UILabel!
#IBOutlet var entryLabel: UILabel!
}
'''
I have come up with 2 solutions to this problem, without having the parent view controller know about its subclass.
In the first example the parent sets properties on itself that the child listens to (via the didSet method, it then updates its view accordingly. However, this isn't ideal because the entryDate and entry string fields are useless on their own, almost redundant in the parent.
class ParentViewController: UIViewController {
var entryDate: String?
var entry: String?
#IBAction func leavingView(){
self.entryDate = ""
self.entry = ""
self.dismiss(animated: true, completion: nil)
}
}
class ChildViewController: ParentViewController {
#IBOutlet var entryDateLabel: UILabel!
#IBOutlet var entryLabel: UILabel!
override var entryDate: String? {
didSet {
guard isViewLoaded else {
return
}
entryDateLabel.text = entryDate
}
}
override var entry: String? {
didSet {
guard isViewLoaded else {
return
}
entryLabel.text = entry
}
}
}
In my opinion, the second solution is clearer and keeps implementation details more separate because you're using instructions or events to notify the child view controllers.
class ParentViewController: UIViewController {
#IBAction func leavingView(){
self.dismiss(animated: true, completion: didLeaveView)
}
func didLeaveView() { }
}
class ChildViewController: ParentViewController {
#IBOutlet var entryDateLabel: UILabel!
#IBOutlet var entryLabel: UILabel!
override func didLeaveView() {
entryDateLabel.text = ""
entryLabel.text = ""
}
}
Since your requirement is not that much clear I have created a demo for you and into that demo I have added child ContainerViewController into parent ViewController and from that parent view controller you can change UILabel text when you click on UIButton of parent ViewController and code will be for ViewController
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
}
#IBAction func btnFromParentViewTapped(_ sender: Any) {
//Here get the child of your parent view controller
if let containerView = self.children[0] as? ContainerViewController {
containerView.lblContainer.text = ""
}
}
}
and ContainerViewController code will be:
class ContainerViewController: UIViewController {
#IBOutlet weak var lblContainer: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
}
Don't need to add much here because you are accessing it from parent view.
And your result will be:
As you can see when I click on button which title says Change Container label text the label text from ContainerViewController set to empty string.
For more info check THIS demo project.
I'm having issues with passing a custom protocol (MainWindowControllerProtocol) to the EditorViewController from the MainWindowController, which is subclass of NSWindowController. Please help.
EditorViewController.swift
extension EditorViewController: MainWindowControllerProtocol {
func didOpenFile() {
print("TODO: Open File") // never called, but it should be
}
}
class EditorViewController: NSViewController {
// - IBOutlets
#IBOutlet weak var treeOutlineView: NSOutlineView!
#IBOutlet var codeTextView: NSTextView!
#IBOutlet weak var counterTextField: NSTextField!
#IBOutlet weak var languageTextField: NSTextField!
//public var editor = Editor()
//var rootNode: Node?
override func viewDidLoad() {
super.viewDidLoad()
// Do view setup here.
//rootNode = Path(Path.userDownloads).node
// Issue is here
if let windowController = NSApplication.shared.mainWindow?.windowController as? MainWindowController {
windowController.delegate = self
}
else {
print("Doesnt work") // prints this
}
//treeOutlineView.reloadData()
}
}
MainWindowController
public protocol MainWindowControllerProtocol {
func didOpenFile()
}
class MainWindowController: NSWindowController {
var delegate: MainWindowControllerProtocol?
override func windowDidLoad() {
super.windowDidLoad()
// Implement this method to handle any initialization after your window controller's window has been loaded from its nib file.
}
#IBAction func openFile(_ sender: Any) {
print("In here") // this is called?
delegate?.didOpenFile() // but this never is apparently
}
}
Maybe this topic should help.
This method might return nil if the application’s nib file hasn’t
finished loading, if the receiver is not active, or if the application
is hidden.
Have you checked if NSApplication.shared.mainWindow is nil or just NSApplication.shared.mainWindow?.windowController cannot be casted to your controller class ?
I'm very new to Swift MacOS programming and have been learning by writing small test applications.
The aim of this application is to enable the pushbutton when the 2nd textfield has the focus, and disable it when it is not focused.
I have found that by subclassing the NSTextField I can override becomeFirstResponder() however don't know how to set the button to be disabled from the subclass.
ViewController:
class ViewController: NSViewController {
#IBOutlet public weak var pushButton: NSButton!
#IBOutlet weak var textField3: NSTextField!
#IBOutlet weak var textField2: GSTextField!
#IBOutlet weak var textField1: NSTextField!
override func viewDidLoad() {
super.viewDidLoad()
textField2.delegate = self
// Do any additional setup after loading the view.
}
override var representedObject: Any? {
didSet {
// Update the view, if already loaded.
}
}
func chgButton(onoff: Bool){
pushButton.isEnabled = onoff
}
}
// When the field completes editing make the pushbutton disabled.
extension ViewController: NSTextFieldDelegate {
override func controlTextDidEndEditing(_ obj: Notification) {
print("did end")
chgButton(onoff: false)
}
}
GSTextField.Swift
class GSTextField: NSTextField {
override func becomeFirstResponder() -> Bool {
print("GSTextField Firstresponder")
////*** I need to set the button to be enabled here
return super.becomeFirstResponder()
}
}
Your NSTextField subclass needs to be able to communicate with the pushButton. The easiest way to do this is to pass a reference to the pushButton to your text field and then update the push button from there.
Update your ViewController like this:
override func viewDidLoad() {
super.viewDidLoad()
textField2.delegate = self
textField2.pushButton = pushButton
// Do any additional setup after loading the view.
}
And your GSTextField like this:
class GSTextField: NSTextField {
weak var pushButton: NSButton?
override func becomeFirstResponder() -> Bool {
print("GSTextField Firstresponder")
pushButton?.isEnabled = true
return super.becomeFirstResponder()
}
override func resignFirstResponder() -> Bool {
pushButton?.isEnabled = false
return super.resignFirstResponder()
}
}
It should be noted that while this works fine in this toy example, this is a sub-optimal solution to this problem because it tightly couples the pushButton and the GSTextField. A better solution would be to use delegation to communicate the focus changes to the ViewController, and let the ViewController handle the updates.
Your GSTextField would look like this:
protocol FocusObservable: class {
func didGainFocus(sender: Any)
func didLoseFocus(sender: Any)
}
class GSTextField: NSTextField {
weak var focusDelegate: FocusObservable?
override func becomeFirstResponder() -> Bool {
print("GSTextField Firstresponder")
focusDelegate?.didGainFocus(sender: self)
return super.becomeFirstResponder()
}
override func resignFirstResponder() -> Bool {
focusDelegate?.didLoseFocus(sender: self)
return super.resignFirstResponder()
}
}
And then you would add protocol conformance to the ViewController:
extension ViewController: FocusObservable {
func didGainFocus(sender: Any) {
pushButton.isEnabled = true
}
func didLoseFocus(sender: Any) {
pushButton.isEnabled = false
}
}
and set the focusDelegate of the text field:
override func viewDidLoad() {
super.viewDidLoad()
textField2.delegate = self
textField2.focusDelegate = self
// Do any additional setup after loading the view.
}
This is the error Xcode outputs
Unexpectedly found nil while unwrapping an Optional value
I have a viewcontroller that has a tableview and a few buttons; the buttons allow me to insert or remove data. It seems that when I click on Add (which brings up a new viewcontroller via segue as a sheet) the app crashes with the error above. Clicking on remove doesn't have this affect. So it has to do with something regarding the new viewcontroller as a guess. The console doesn't go further into the error other than printing out (lldb)
Here's my code
override func viewDidLoad() {
super.viewDidLoad()
alarmTableView.dataSource = self //error occurs here
alarmTableView.delegate = self //if i remove the above line if will occur here too.
}
My Viewcontroller which the above viewDidLoad func is embedded lists the protocols I need
class ViewController: NSViewController, NSTableViewDelegate, NSTableViewDataSource {
#IBOutlet weak var addAlarm: NSButton!
#IBOutlet weak var resetDataButton: NSButton!
#IBOutlet var alarmArrayController: NSArrayController!
#IBOutlet weak var alarmTableView: NSTableView!
#IBOutlet weak var deleteAll: NSButton!
#objc let moc: NSManagedObjectContext
required init?(coder: NSCoder) {
self.moc = CoreDataHandler.getContext()
super.init(coder: coder)
}
override func prepare(for segue: NSStoryboardSegue, sender: Any?) {
let destinationController = segue.destinationController as! AddAlarmViewController
//pass data to next controller here
}
#IBAction func deleteAllAction(_ sender: Any) {
if (alarmTableView.selectedRow >= 0) {
if (CoreDataHandler.deleteAllObjectsInEntity(entityName: "Alarm")) {
//remove from nsarray controller
for object in alarmArrayController.arrangedObjects as! [Alarm] {
print(object)
alarmArrayController.removeObject(object)
}
alarmTableView.reloadData()
}
}
else {
printInfo(str: "There are no alarms to delete")
}
}
/* Response to the remove alarm button - It removes a selected alarm object from the table */
#IBAction func resetDataAction(_ sender: Any) {
if (alarmTableView.selectedRow >= 0) {
let selectedAlarm = self.alarmArrayController.selectedObjects.first as! Alarm
alarmArrayController.remove(atArrangedObjectIndex: alarmTableView.selectedRow)
CoreDataHandler.deleteObjectInEntity(entityName: "Alarm", obj: selectedAlarm)
alarmTableView.reloadData()
}
else {
//will need a warning or play a sound.
printInfo(str: "Please select an alarm")
}
}
override func viewDidLoad() {
super.viewDidLoad()
printInfo(str: "viewdidload")
print(alarmTableView)
if (alarmTableView != nil) {
printInfo(str: "AlarmTableView Is initialised")
alarmTableView.dataSource = self
alarmTableView.delegate = self
}
else {
printInfo(str: "AlarmTableView is not initialised")
}
}
override var representedObject: Any? {
didSet {
// Update the view, if already loaded.
}
}
func printInfo(str: String) {
print("ViewController: \(str)")
}
func tableView(_ tableView: NSTableView, heightOfRow row: Int) -> CGFloat {
return 100.0
}
}
class AddAlarmViewController: ViewController {
#IBOutlet weak var closeButton: NSButton!
override func viewDidLoad() {
super.viewDidLoad()
// Do view setup here.
printClassInfo(str: "viewDidLoad")
CoreDataHandler.saveTestData()
}
#IBAction func closeButtonAction(_ sender: Any) {
self.dismissViewController(self)
}
func printClassInfo(str: String) {
print("AddAlarmViewController \(str)")
}
}
If I remove the lines where the error occurs the app run fine. But I want to override the delegate and datasource and use the functions to further customise the table. I'm also using Cocoa Bindings.
Why am I getting this error?
Update
I haven't solved it yet, but i placed a couple of print statements in my viewDidLoad function. It seems that when the app is first loaded, the table view is initialised. But after when I clicked on the Add button, the table view is then set to nil for some odd reason, as if another table view has been initialised. However the data is still visible
Problem:
class AddAlarmViewController: ViewController {
//...
override func viewDidLoad() {
super.viewDidLoad()
//...
}
}
Your AddAlarmViewController is a subclass of ViewController instead of NSViewController.
In AddAlarmViewController's viewDidLoad you call super.viewDidLoad() which basically calls ViewController's viewDidLoad.
But... in this case ViewController is a new instance as the super class of AddAlarmViewController and none of it's properties are initialized.
Whatever it be, it's probably not what you want.
Solution:
class AddAlarmViewController: NSViewController {
//... rest as it is
}
in my view controller, i have set up like this.
protocol MenuDelegate {
func updateIndexOfMenuExpanded(index: Bool)
}
class ViewController: UIViewController,UITableViewDataSource, UITableViewDelegate {
var delegate : MenuDelegate?
func performaction() -> Void{
delegate!.updateIndexOfMenuExpanded(false)
}
}
and in my baseviewcontroller
class BaseViewController: UIViewController, MenuDelegate{
func updateIndexOfMenuExpanded(index: Bool){
self.menuIsExpanded = index
}
}
please help. thank you.
You have to set the delegate first.
let viewController = ViewController()
let baseViewController = BaseViewController()
viewController.delegate = baseViewController
It would also be wise to make the delegate a weak reference and to not force unwrap with !.
class ViewController: UIViewController,UITableViewDataSource, UITableViewDelegate {
weak var delegate : MenuDelegate?
func performaction() {
delegate?.updateIndexOfMenuExpanded(false)
}
}
Delegate is used when you want to pass data between viewcontrollers.this aproach is one to one
Here is the answer how to pass data using delegate
in viewcontroller
define protocol in view controller
protocol ViewController1BackClicked {
func btnBackClicked(str : String)
}
class ViewController1: UIViewController {
var strTitle : String?
var delegate : ViewController1BackClicked?
override func viewDidLoad() {
super.viewDidLoad()
if strTitle != nil{
title = strTitle
}
}
override func viewWillDisappear(animated: Bool) {
delegate?.btnBackClicked("Krutarth")
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
now Protocol is created.to pass data in another view controller
viewcontroller 1 we want to access data
func btnBackClicked(str: String) {
title = str
}
output : Krutarth
this is example how to use protocol