I have a class called AccountPanelController that contains two variables: an IBOutlet to an NSTableView, as well as a simple Int. When I run my app, awakeFromNib: prints that both the NSTableView and the Int have been initialized. From another file, I have created and initialized an instance of the class AcountPanelController. Via a button connected to that other file, I call openPanel: on the instance. At that point accountTable does not exist but somehow number does. In other words, when I initialize the instance of my class the Int is being created, but the NSTableView, an IBOutlet, is not. Why is this? I assume it is because accountTable is an IBOutlet, and therefore will not reinitialize. What can I do about this? (Xcode Version 6.1.1 (6A2008a), Cocoa, Swift)
Thanks,
bigelerow
class AccountPanelController: NSObject, NSTableViewDataSource {
#IBOutlet weak var accountTable: NSTableView!
var number: Int = 5
override func awakeFromNib() {
println(accountTable) // prints "<NSTableView: 0x100512aa0>"
println(number) // prints "5"
}
func openPanel() {
println(number) // prints "5"
println(accountTable) // prints "nil"
accountTable.reloadData() // throws error "unexpectedly found nil while unwrapping an Optional value"
}
// NSTableView data source functions below...
}
Other File
#IBAction func buttonPressed(sender: AnyObject?) {
var instance = AccountPanelController()
instance.openPanel()
}
IB automatically creates instances of all objects with IBOutlets when their xib file is loaded. So, instead of creating my own, second, instance in another file:
var instance = AccountPanelController()
I simply made a reference to the instance IB had already made for me:
IBOutlet weak var IBInstance: AcountPanelController!
Unlike the second instance, this IB created version contained initialized IBOutlets. When I referenced AccountTable it was not nil.
Related
My app has a hierarchy of classes for creating custom view controllers.
The first class is AppViewController. It extends NSViewController and contains methods common to all of my view controllers, like displaying alerts, retrieving data from the database, and so forth. It does not define any variables.
class AppViewController: NSViewController
{
...
}
The next class is ListViewController and is common to all of my "list" views. These are views that contain a single NSTableView with a list of all of the records from the associated database table. It extends AppViewController and conforms to the usual protocols.
Note that this class is generic so that it can properly handle the different views and data models.
class ListViewController<Model: RestModel>: AppViewController,
NSWindowDelegate,
NSTableViewDataSource,
NSTableViewDelegate
{
...
}
ListViewController defines a number of variables, including an IBOutlet for an NSTableView. That outlet is not wired to anything in the storyboard. The plan is to set it at run-time.
ListViewController also defines various functions including viewDidLoad(), viewWillAppear(), a number of app-specific functions, and so on.
The last class is specific to a database model and view, in this case, the Customers view. It extends ListViewController.
class Clv: ListViewController<CustomerMaster>
{
...
}
CustomerMaster is a concrete class that conforms to the RestModel protocol.
The problem:
The strange thing is that the last class, Clv, does not show up in the storyboard's Custom Class: Class pull-down menu, meaning that I cannot specify it as the custom class for my view.
I tried just typing it in, but that results in a run-time error
Unknown class _TtC9Inventory3Clv in Interface Builder file ...
If I remove the <Model: RestModel> from the ListViewController class definition and also remove the <CustomerMaster> from the Clv class definition, the Clv class then appears in the Class menu (of course that doesn't really help, just an observation).
AppViewController and ListViewController both do appear in that menu.
I am at a loss.
Earlier this year I created a similar architecture for an app, and I have to tell you: It can't work with storyboards, as those don't know anything about generics during instantiation.
What works is using nibs though, as you than still can init your view controller yourself.
an example:
import UIKit
class ViewController<Model: Any>: UIViewController {
var model:Model?
}
You can instantiate this view controller like
let vc = ViewController<ListItem>(nibName: "ListViewController", bundle: nil)
or subclass it
class ListViewController: ViewController<ListItem> {
}
and instantiate it like
let vc = ListViewController(nibName: "ListViewController", bundle: nil)
Now it compiles and runs, but you haven't gained much yet, as you cannot wire up your nib with generic properties.
But what you could do is to have a UIView-typed IBOutlet in a non-generic base view controller, subclass it with a generic view controller that has two generic contracts: one for the model, one for the view, ass you most likely want this to be adapted for your model. But now you must have some code that knows how to bring your model on the view. I call this renderer, but you will also find many examples were such an class is called Presenter.
The view controllers:
class BaseRenderViewController: UIViewController {
var renderer: RenderType?
#IBOutlet private weak var privateRenderView: UIView!
var renderView: UIView! {
get { return privateRenderView }
set { privateRenderView = newValue }
}
}
class RenderedContentViewController<Content, View: UIView>: BaseRenderViewController {
var contentRenderer: ContentRenderer<Content, View>? {
return renderer as? ContentRenderer<Content, View>
}
open
override func viewDidLoad() {
super.viewDidLoad()
guard let renderer = contentRenderer, let view = self.renderView as? View else {
return
}
do {
try renderer.render(on: view)
} catch (let error) {
print(error)
}
}
}
The renderers:
protocol RenderType {}
class Renderer<View: UIView>: RenderType {
func render(on view: View) throws {
throw RendererError.methodNotOverridden("\(#function) must be overridden")
}
}
class ContentRenderer<Content, View: UIView>: Renderer<View> {
init(contents: [Content]) {
self.contents = contents
}
let contents: [Content]
override func render(on view: View) throws {
throw RendererError.methodNotOverridden("\(#function) must be overridden")
}
}
You can now subclass ContentRenderer and overwrite the render method to show your content on the view.
tl;dr
By using the approach I just illustrated you can combine any generic view controller with different models, renderers and views. You gain an incredible flexibility — but you won't be able to use storyboards with it.
The answer by #vikingosegundo, while explaining Xcode's complaint and being generally very informative, didn't help me solve my particular problem. My project was started in Xcode 8.3.3 and I already have lots of windows and views in the storyboard so I don't really want to abandon or work around the storyboard/generic issue.
That being said, I did some more research and came to the realization that many people prefer delegation to class inheritance so I decided to explore that approach. I was able to get something working that satisfies my needs.
I present here, a simplified, but functional approach.
First, a protocol that our data models must conform to:
protocol RestModel
{
static var entityName: String { get }
var id: Int { get }
}
Next, a data model:
///
/// A dummy model for testing. It has two properties: an ID and a name.
///
class ModelOne: RestModel
{
static var entityName: String = "ModelOne"
var id: Int
var name: String
init(_ id: Int, _ name: String)
{
self.id = id
self.name = name
}
}
Then, a protocol to which all classes that extend our base class must conform:
///
/// Protocol: ListViewControllerDelegate
///
/// All classes that extend BaseListViewController must conform to this
/// protocol. This allows us to separate all knowledge of the actual data
/// source, record formats, etc. into a view-specific controller.
///
protocol ListViewControllerDelegate: class
{
///
/// The actual table view object. This must be defined in the extending class
/// as #IBOutlet weak var tableView: NSTableView!. The base class saves a weak
/// reference to this variable in one of its local variables and uses that
/// variable to access the actual table view object.
///
weak var tableView: NSTableView! { get }
///
/// This method must perform whatever I/O is required to load the data for the
/// table view. Loading the data is assumed to be asyncronous so the method
/// must accept a closure which must be called after the data has been loaded.
///
func loadRecords()
///
/// This method must simply return the number of rows in the data set.
///
func numberOfRows() -> Int
///
/// This method must return the text that is to be displayed in the specified
/// cell.
/// - parameters:
/// - row: The row number (as supplied in the call to tableView(tableView:viewFor:row:).
/// - col: The column identifier (from tableColumn.identifier).
/// - returns: String
///
func textForCell(row: Int, col: String) -> String
} // ListViewControllerDelegate protocol
Now the actual base class:
class BaseListViewController: NSViewController,
NSTableViewDataSource,
NSTableViewDelegate
{
//
// The instance of the extending class. Like most delegate variables in Cocoa
// applications, this variable must be set by the delegate (the extending
// class, in this case).
//
weak var delegate: ListViewControllerDelegate?
//
// The extending class' actual table view object.
//
weak var delegateTableView: NSTableView!
//
// Calls super.viewDidLoad()
// Gets a reference to the extending class' table view object.
// Sets the data source and delegate for the table view.
// Calls the delegate's loadRecords() method.
//
override func viewDidLoad()
{
super.viewDidLoad()
delegateTableView = delegate?.tableView
delegateTableView.dataSource = self
delegateTableView.delegate = self
delegate?.loadRecords()
delegateTableView.reloadData()
}
//
// This is called by the extending class' table view object to retreive the
// number of rows in the data set.
//
func numberOfRows(in tableView: NSTableView) -> Int
{
return (delegate?.numberOfRows())!
}
//
// This is called by the extending class' table view to retrieve a view cell
// for each column/row in the table. We call the delegate's textForCell(row:col:)
// method to retrieve the text and then create a view cell with that as its
// contents.
//
func tableView(_ tableView: NSTableView, viewFor tableColumn: NSTableColumn?, row: Int) -> NSView?
{
if let col = tableColumn?.identifier, let text = delegate?.textForCell(row: row, col: col)
{
if let cell = delegate?.tableView.make(withIdentifier: (tableColumn?.identifier)!, owner: nil) as? NSTableCellView
{
cell.textField?.stringValue = text
return cell
}
}
return nil
}
} // BaseListViewController{}
And, finally, an extending class:
///
/// A concrete example class that extends BaseListViewController{}.
/// It loadRecords() method simply uses a hard-coded list.
/// This is the class that is specified in the IB.
///
class ViewOne: BaseListViewController, ListViewControllerDelegate
{
var records: [ModelOne] = []
//
// The actual table view in our view.
//
#IBOutlet weak var tableView: NSTableView!
override func viewDidLoad()
{
super.delegate = self
super.viewDidLoad()
}
func loadRecords()
{
records =
[
ModelOne(1, "AAA"),
ModelOne(2, "BBB"),
ModelOne(3, "CCC"),
ModelOne(4, "DDD"),
]
}
func numberOfRows() -> Int
{
return records.count
}
func textForCell(row: Int, col: String) -> String
{
switch col
{
case "id":
return "\(records[row].id)"
case "name":
return records[row].name
default:
return ""
}
}
} // ViewOne{}
This is, of course, a simplified prototype. In a real-world implementation, loading the records and updating the table would happen in closures after asynchronously loading the data from a database, web service, or some such.
My full prototype defines two models and two view controllers that extend BaseListViewClass. It works as desired. The production version of the base class will contain numerous other methods (which is why a wanted it to be a base class in the first place :-)
My question is simple , I have an IBoutlet(of a label) declared in a class , I need to change it content from another class , is that possible ?
edit : The view of the IBoutlet is loaded in the other class through a scroll view
the first class :
var historyVariable = ""
class FirstViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
// here a code to set a value to historyVariable when button pressed
Text().call()
}
}
the second class
class Text: UIViewController {
#IBOutlet var History: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
}
func call() {
History.text = "\(historyVariable)"
}
}
it gives me an error unexpectedly found nil while unwrapping an Optional value when trying to set the text to the History label
Assuming text() is actually Text(), that would create a new, empty Text object. Since it's not part of the controller hierarchy, its view and other outlets aren't loaded at the time you invoke call().
You either need to instantiate the Text controller from a storyboard (or otherwise) and present it so that it's properly initialized or else use one that's already active...if that's your intent.
I'm starting to learn Swift.
I've a viewController that has a var which needs updating from an outside viewController. So I added public to its declaration but my code won't compile because my class is internal (by default). So i make my class public but then it forces me to make all functions inside my class public including viewDidLoad, the tableView dataSource and delegate methods. What am i doing wrong? I don't want anyone else to call my controller's viewDidLoad.
All I wanted to viewControllerA to access a var inside viewControllerB without exposing every function inside viewControllerB to the outside world.
In ObjC, this can be achieved very easily by marking the property readonly in the headerfile and readwrite in the implementation. In this case, I would've the property in the header file so it's read-writable from outside.
here's some pseudo code
class MyViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
var myTitle: NSString?
override func viewDidLoad() {
super.viewDidLoad()
}
}
// objC part
MyViewController *myViewController = [[MyViewController alloc] initWithNibName:#"MyViewController" bundle:nil];
myViewController.myTitle = #""; // not available
Now if i make myTitle a public var, i get this error
Declaring a public var for an internal class
So I make MyViewController a public class.
Now i get bunch of errors
Method 'tableView(_:numberOfRowsInSection:)' must be declared public
because it matches a requirement in public protocol
'UITableViewDataSource'
You could make a protocol to save and access data across view controllers. Here's one way to do it.
// Make a custom protocol delegate with a method to store the variable. In this case I'll store a boolean.
protocol storeViewControllerBVariableDelegate {
func storeVariable(data: Bool?)
}
// In your view controller A, assign your custom protocol delegate to it and add the new delegate method.
class viewControllerA: UIViewController, storeViewControllerBVariableDelegate {
func storeVariable(data: Bool?) {
self.variableName = data
}
}
// In your view controller A's prepare for segue, assign the stored variable to view controller B if you wanted to pass it forward and backward between view controllers.
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
let viewControllerB = segue.destinationViewController as! viewControllerB
viewControllerB.variableName = variableName
}
// In your view controller B, initialize a variable and assign it to the delegate.
class viewControllerB: UIViewController {
var variableName: Bool!
var delegate: storeViewControllerBVariableDelegate?
// However you want to save the variable in view controller B, you can do so in an IBAction, viewDidLoad, etc.
#IBAction func saveVariable(sender: UIButton) {
delegate?.storeVariable(self.variableName)
}
}
Here are two solutions that I can think of for passing variables between view controllers
Global Option
ViewController2.swift
import UIKit
var globalVariable = String()
class ViewController1: UIViewConroller {
}
ViewController2.swift
class ViewController2: UIViewController {
overload func viewDidLoad() {
globalVariable = "some string data"
}
}
you can now access that variable globally.
Segue Option
I think a better way to handle sending data back and forth between View Controllers is by using delegates and the prepareForSegue function which is covered in depth here.
You declare your prepareForSegue function like so:
View Controller 1
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if(segue.identifier == "yourIdentifierInStoryboard") {
var yourNextViewController = (segue.destinationViewController as yourNextViewControllerClass)
yourNextViewController.value = yourValue
ViewController 2
class yourNextViewControllerClass {
var value:Int! // or whatever
The you can call it programmatically
self.performSegueWithIdentifier("yourIdentifierInStoryboard", sender: self)
If you want to set values back from your second View Controller, you can use a delegate Method, to respect the original author of this content I'll redirect you to his post:
Read the rest from the original post.
I am encountering a strange error:
2015-04-02 12:20:14.642 test[21167:257788] Failed to connect
(testApp) outlet from (test.AppDelegate) to (NSMenuItem): missing
setter or instance variable
inserted id: 122
I occured when a added a menuItem to a menu and connected a function to it.
I do not know what the Problem is. The app works fine but i don't think it is a smart idea to ignore the error.
What is meant by setter or instance variable? Why is it needed?
UPDATE: Here is the relevant code:
import Cocoa
import Foundation
#NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate {
#IBOutlet weak var window: NSWindow!
#IBOutlet weak var statusMenu: NSMenu!
let statusItem = NSStatusBar.systemStatusBar().statusItemWithLength(-1)
func applicationDidFinishLaunching(aNotification: NSNotification) {
let icon = NSImage(named: "statusIcon")
statusItem.image = icon
statusItem.menu = statusMenu
// Time for constant repeat
NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: "timerRepeat", userInfo: nil, repeats: true)
}
// Method to call the tracking core
func timerRepeat() {
//....
}
#IBAction func frontEnd(sender: NSMenuItem) {
var targetURL : String = NSBundle.mainBundle().resourcePath!
targetURL = targetURL + "/" + "front.app"
let workspace = NSWorkspace()
workspace.launchApplication(targetURL)
}
#IBAction func menuClicked(sender: NSMenuItem) {
NSApplication.sharedApplication().terminate(self)
}
}
You have a broken outlet in your xib file. Usually it happens when you set up an outlet to ivar or property which is later deleted or renamed not using Xcode's rename feature.
Also make sure that your custom view or view controller class is added to your target. (Project => Target Name => Build Phases => Compile Sources). It's possible that a file is in your project but not your target.
This happens because you at one point created an #IBOutlet for a storyboard element. You then later removed the code (reference) from your swift file.
I created an example where I create two extra #IBOutlets (I named them 'correctField' and 'incorrectField'- both are incorrect though) and connected them from my storyboard to my swift file.
I then removed the code from my swift file. This generates the log as shown in the following figure :
To remove this kind of log message, you can do the following:
Go to the 'storyboard' and select the storyboard elements you created connections (#IBOutlets) from.
Open the 'connection inspector' as showed in the figure below
Remove the Referencing Outlets which are incorrect (in my case it is the 'correctField' and 'incorrectField')
Done
This was done in xCode 11
I have had bad luck finding any examples on the web that closely match what I am trying to do. I am trying to using NSPageController to view and switch between multiple NSPageControllers. My steps.
I create a new OS X swift project
I add an object to the ViewController and make it of NSPageController class.
I add two buttons, one I label "Next" and the other one I label "Back" for the transitions.
I link the buttons to the NSPageController object as navigateForward and navigateBack actions.
I create an outlet in the custom NSViewController class for the NSPageController object and add the specific NSPageController delegate methods.
I add two additional view controllers in storyboard and create an identifier for them to reference back in my custom view controller class: Wizard1, Wizard2.
import Cocoa
class ViewController: NSViewController, NSPageControllerDelegate {
#IBOutlet var myPageController: NSPageController!
override func viewDidLoad() {
super.viewDidLoad()
let vc1: AnyObject? = self.storyboard!.instantiateControllerWithIdentifier("Wizard1")
let vc2: AnyObject? = self.storyboard!.instantiateControllerWithIdentifier("Wizard2")
self.myPageController.arrangedObjects.append(vc1!)
self.myPageController.arrangedObjects.append(vc2!)
// Do any additional setup after loading the view.
}
override init?(nibName nibNameOrNil: String?, bundle nibBundleOrNil: NSBundle?) {
myPageController = NSPageController()
super.init(nibName: nibNameOrNil, bundle: nibBundleOrNil?)
}
required init?(coder aDecoder: NSCoder) {
myPageController = NSPageController()
super.init(coder:aDecoder)
}
override var representedObject: AnyObject? {
didSet {
// Update the view, if already loaded.
}
}
func pageController(pageController: NSPageController, identifierForObject object: AnyObject!) -> String! {
return "View"
}
func pageController(pageController: NSPageController, viewControllerForIdentifier identifier: String!) -> NSViewController! {
let vc1: AnyObject? = self.storyboard!.instantiateControllerWithIdentifier("Wizard1")
return vc1 as NSViewController
}
func pageController(pageController: NSPageController, prepareViewController viewController: NSViewController!, withObject object: AnyObject!) {
viewController.representedObject = object
}
func pageControllerDidEndLiveTransition(pageController: NSPageController) {
pageController.completeTransition()
}
func pageControllerWillStartLiveTransition(pageController: NSPageController) {
self.presentViewControllerAsModalWindow(self.storyboard?.instantiateControllerWithIdentifier("Wizard2") as NSViewController)
}
}
The error I get when pressing the Next button is:
-[NSNib initWithNibNamed:bundle:] could not load the nibName: NSPageController in bundle (null).
Perhaps you are trying to load a nib with the wrong name in AppDelegate.m or wherever you are initializing your page controller.
Otherwise you have missed creating a .xib file and to name it NSPageController. When creating a Cocoa Touch Class there is a checkbox to also create an xib file for your class if needed.
This line is responsible for the error:
myPageController = NSPageController()
You're trying to initialize a view controller without a nib, that's why it does not work. By default the NSViewController's name is taken to identify the nib that corresponds to it. In your case it is "NSPageController".