I am trying to update a label in an NSViewController from a NSWindowController.
Here is what I've done.
Created a protocol:
protocol PopoverProtocol: class {
func SearchForIt(Query:String)
}
Created a function to update the label in the NSViewController
class PopoverController: NSViewController, PopoverProtocol {
#IBOutlet weak var Label: NSTextField!
func SearchForIt(Query:String){
Label.stringValue = Query
}
}
Called the protocol and function from the NSWindowController
class TutorialViewController: NSWindowController, NSSearchFieldDelegate {
weak var responder : PopoverProtocol?
#IBAction override func controlTextDidChange(obj: NSNotification) {
PopoVer.showRelativeToRect(SearchField.bounds, ofView: SearchField, preferredEdge: NSRectEdge.MinY)
responder?.SearchForIt(SearchField.stringValue)
}
}
However nothing is happening. I am not getting any error messages, the function SearchForIt is just not being called.
Any ideas on what I am doing wrong ? Thank you for your help !
A protocol is adopted by a class as you did in your second block of code above. Now your view controller has to implement the SearchForIt method and then your view controller can take the call, not a separately defined object.
In your controlTextDidChange, replace responder with your viewcontroller instance.
Related
I have a UIbutton class - from which I would like to call an 'adjust constraints' method after the user makes changes on the setting screen. I have created some protocols and all seems in order but it is not calling the method from the subview UIButton after the user closes the Setting Screen.
I have tried some of the other solutions here - that hasn't worked and I think it might be because I am using a UIButton class and I can't reinstantiate it, or call the instantiation? Either way, it never calls the method from the delegate.
Is using protocols the right way to solve this problem and if so, what am I missing?
Basically I have 3 files; the MainVC which I set as my first delegate (it gets triggered from my SettingScreenVC when user is done making changes to Setting Screen):
class MainVC: UIViewController, SettingScreenDelegate {
weak var numButtonDelegate: Buttons_Numeric?
func settingSetButtonConstraints() {
numButtonDelegate?.setupButtonConstraints()
}
}
Then in my Setting Screen I call the MainVC after the user made some changes to their settings:
class MainVC: SettingScreenVC {
weak var delegate: SettingScreenDelegate?
func closeSettings() {
delegate?.settingSetButtonConstraints()
}
}
Then in my Buttons_Numeric class I declare the function and the UIButton class delegate:
protocol numButtonDelegate: class {
func setupButtonConstraints()
}
class Buttons_Numeric: UIButton, numButtonDelegate {
weak var numButtonDelegate: Buttons_Numeric?
required init(coder aDecoder:NSCoder) { super.init(coder: aDecoder)!}
override init(frame:CGRect) {super.init(frame: frame)
self.numButtonDelegate = self
setupButtonConstraints()
}
override func awakeFromNib() {
self.numButtonDelegate = self
setupButtonConstraints()
}
func setupButtonConstraints() {
//SET UP CONSTRAINTS
}
}
Ok so couple of things you need to understand about delegates:
if you create a delegate, you need to conform to the delegate somewhere.
the conforming class should be assigned to the instance of the delegate.
With that in mind lets try to fix the code:
first the settings screen:
protocol SettingScreenDelegate: class {
func settingSetButtonConstraints()
}
class SettingScreenVC {
weak var delegate: SettingScreenDelegate?
func closeSettings() {
delegate?.settingSetButtonConstraints()
}
}
So far so good now the mainScreen should conform to the SettingScreenDelegate and be assigned to its delegate:
class MainVC: UIViewController, SettingScreenDelegate {
weak var button: Buttons_Numeric!
func openSettingsScreen() {
let settingsScreen = ... // the setting screen instanciation
settingsScreen.delegate = self // the MainVC
}
func settingSetButtonConstraints() {
self.button.setupButtonConstraints()
}
}
Now for the last step, the MainVC should have an instance of the button, then the only thing we need to do is call the function 'setupButtonConstraints' from the MainVC which means we do not need the delegate at the button.
class Buttons_Numeric: UIButton {
required init(coder aDecoder:NSCoder) { super.init(coder: aDecoder)!}
override init(frame:CGRect) {super.init(frame: frame)
setupButtonConstraints()
}
override func awakeFromNib() {
setupButtonConstraints()
}
func setupButtonConstraints() {
//SET UP CONSTRAINTS
}
}
You need to assign a value to the delegate variable. I would do it like this if the answer is always self
class Example: SomeDelegate {
lazy var someDelegate: SomeDelegate? = self
}
Otherwise you'll want to do it in the class' initializer or ViewDidLoad.
I am beginner of swift. I tried to use array's append method in my code but it doesn't work. How should I implement the array correctly?
The error messages:
Swift Compiler Error Group
ViewController.swift:16:5: Expected declaration
ViewController.swift:11:7: In declaration of 'ViewController'
I tried to use array's append method in my code but it doesn't work.
import UIKit
class ViewController: UIViewController { //Error msg: In declaration of 'ViewController'
#IBOutlet weak var dice: UIImageView!
#IBOutlet weak var dice2: UIImageView!
var dices : [String] = []
dices.append("Hi") //Error: Expected declaration
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
}
#IBAction func rollPressed(_ sender: UIButton) {
dice.image = UIImage(named: "dice3")
}
}
I expect I can add "hi" into the array dices.
You should call the append inside a function after the vc is fully initated
class ViewController: UIViewController { //Error msg: In declaration of 'ViewController'
#IBOutlet weak var dice: UIImageView!
#IBOutlet weak var dice2: UIImageView!
var dices : [String] = []
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
dices.append("Hi") // e.x here
}
#IBAction func rollPressed(_ sender: UIButton) {
dice.image = UIImage(named: "dice3")
}
}
Or replace
var dices : [String] = []
with
var dices = ["Hi"]
SH_Khan is right. I'll explain why though.
When defining a class, the first level of indentation is only for its methods and properties, aka func, var, and let. (You can also define other classes/structs/enums in there too)
Calling those functions or system functions like Array.append() or print("dog sweat") must happen inside of another function. The reason why is that your application's live logic is literally just functions all the way down. No function gets called unless it's inside of another function first. (The only exceptions are Swift's quick and dirty initializations like setting a default value to a var outside of an init() { } or another function.)
A dog doesn't wake up from its nap unless you make some noise. It won't do it on its own. (crappy metaphor, but yeah)
I hope that made any sense.
I have a singleton to store some global data for my macOS app, one of my ViewController keeps modifying data. I want to simultaneously show the changes in a View, which is related to another ViewController. what 's the best way to do this?
Global Data:
final class AppData {
static var logs: [LogData] = []
}
ViewController 1:
class FirstViewController: NSViewController {
AppData.logs.append(newLogData)
}
ViewController 2:
class SecondViewController: NSViewController {
// what's the best way to simultaneously watch the change of AppData.logs?
}
If your App is planned to be macOS only you can use a NSObjectController. This is definitively the easiest approach and you can do most of the configuration in Interface builder. It works internally with bindings. In case of an array you want to observe, you would use a NSArrayController.
One way is to use the notificationcenter
In viewcontroller2 add:
override func viewDidLoad() {
super.viewDidLoad()
notificationCenter.default.addObserver(self,
selector: #selector(view1DidChange),
name: "view1DidChange",
object: nil
)
}
#objc private func view1DidChange(_ notification: Notification) {
// Do something
}
In viewcontroller1 add
notificationCenter.default.post(name: "view1DidChange", object: self)
This can be repeated in every class, that should listen.
Here i am sharing the Delegate & Protocol approach to achieve this functionality.
final class AppData {
static var logs: [LogData] = []
}
protocol FirstViewControllerDelegate {
func ViewControllerDelegate(appData:[LogData])
}
class FirstViewController: NSViewController {
var delegate:FirstViewControllerDelegate?
override func viewDidLoad() {
super.viewDidLoad()
AppData.logs.append(newLogData)
self. delegate?.ViewControllerDelegate(appData: AppData.logs)
}
}
class SecondViewController: NSViewController,FirstViewControllerDelegate {
var firstViewController:FirstViewController = FirstViewController()
override func viewDidLoad() {
self.firstViewController.delegate = self
}
func ViewControllerDelegate(appData:[LogData]){
//Do Update the UI
}
}
I'm trying to learn the delegation process for Swift in Xcode 8.
I can get it working just fine, but have a question about the subclass in my delegate. Normally, in Objective-C, the subclass for this would be NSObject. I'm able to get it working with NSObject and AnyObject. I read a article about not crossing Objective-C because of performance. Does this really matter? If it's not a view or any other type of controller, what's the subclass in Swift for an object?
Is AnyObject the same as NSObject?
ViewController
import UIKit
class ViewController: UIViewController, TestDelegate {
// init the delegate
let theDelegate = TheDelegate ()
#IBOutlet weak var label1: UILabel!
#IBAction func button1(_ sender: Any) {
// tell the delegate what to do
theDelegate.run(add: 1)
}
override func viewDidLoad() {
super.viewDidLoad()
theDelegate.delegate = self
}
// the protocol
func didTest(int: Int) {
label1.text = "\(int)"
print ("Got back from delegate \(int)")
}
}
Object TestProtocol.swift
import Foundation
protocol TestDelegate: class {
func didTest(int: Int)
}
class TheDelegate: AnyObject{
weak var delegate: TestDelegate?
func run(add: Int){
let test = add + 1
delegate?.didTest(int: test)
}
}
There is no reason to subclass AnyObject, since everything is an AnyObject just by existing (like object in Java).
NSObject is the old base class in Obj-C, so if you are wanting to have your protocol or class be seen in Obj-C code it must either be marked #objc or it must subclass NSObject.
So unless you are also using Obj-C in your program, then you don't need to subclass NSObject.
Look at
Swift 3: subclassing NSObject or not?
https://developer.apple.com/library/content/documentation/Swift/Conceptual/BuildingCocoaApps/MixandMatch.html
I'm new to using delegates in Swift, and I can't seem to figure out how to communicate with my View Controller from a different class. Specifically, I call the custom class's functions from my App Delegate, and then from within that custom class, I call a function within my View Controller. My basic setup, following this question, is:
AppDelegate.swift:
var customClass = customClass()
func applicationDidFinishLaunching(aNotification: NSNotification) {
customClass.customFunction()
}
CustomClass.swift:
weak var delegate: ViewControllerDelegate?
func customFunction() {
delegate?.delegateMethod(data)
}
ViewController.swift:
protocol ViewControllerDelegate: class {
func customFunction(data: AnyObject)
}
class ViewController: NSViewController, ViewControllerDelegate
func customFunction(data: AnyObject){
println("called")
}
}
However, delegate is always nil. I am assuming this is either because the ViewControllerDelegate protocol never gets initialized or because I never set the delegate of the actual NSViewController? I know I'm missing something obvious/straightfoward, however I have yet to see what that is.
Your question is hard to answers because you have completely misunderstood the point of a protocol.
A protocol is a type which is used to define functionality. A class that conforms to this protocol provides the specified functionality, by implementing the required methods.
You can not initialize a protocol.
So if your CustomClass looks like this:
class CustomClass {
weak var delegate: ViewControllerDelegate?
func customFunction() {
delegate?.delegateMethod(data)
}
}
Why do you expect that delegate has suddenly a value?
Of course you have to set delegate to something first. The delegate must set delegate. If you want a ViewController instance to be the delegate, it must assign itself to delegate.
This for instance will work.
protocol ViewControllerDelegate {
func delegateMethod(data: AnyObject) //I renamed this because in
//CustomClass you are trying to call `delegateMethod` on the delegate
}
class CustomClass {
weak var delegate: ViewControllerDelegate?
func customFunction() {
delegate?.delegateMethod(data)
}
}
class ViewController: NSViewController, ViewControllerDelegate
var customClass = CustomClass()
func viewDidLoad(){
customClass.delegate = self
customClass.customFunction()
}
func delegateMethod(data: AnyObject){
println("called")
}
}
Read more about delegation here.