I am new to OS X app development. I manage to built the NSComboBox (Selectable, not editable), I can get it indexOfSelectedItem on action button click, working fine.
How to detect the the value on change? When user change their selection, what kind of function I shall use to detect the new selected index?
I tried to use the NSNotification but it didn't pass the new change value, always is the default value when load. It is because I place the postNotificationName in wrong place or there are other method should use to get the value on change?
I tried searching the net, video, tutorial but mostly written for Objective-C. I can't find any answer for this in SWIFT.
import Cocoa
class NewProjectSetup: NSViewController {
let comboxRouterValue: [String] = ["No","Yes"]
#IBOutlet weak var projNewRouter: NSComboBox!
#IBAction func btnAddNewProject(sender: AnyObject) {
let comBoxID = projNewRouter.indexOfSelectedItem
print(“Combo Box ID is: \(comBoxID)”)
}
#IBAction func btnCancel(sender: AnyObject) {
self.dismissViewController(self)
}
override func viewDidLoad() {
super.viewDidLoad()
addComboxValue(comboxRouterValue,myObj:projNewRouter)
self.projNewRouter.selectItemAtIndex(0)
let notificationCenter = NSNotificationCenter.defaultCenter()
notificationCenter.addObserver(
self,
selector: “testNotication:”,
name:"NotificationIdentifier",
object: nil)
NSNotificationCenter.defaultCenter().postNotificationName("NotificationIdentifier", object: projNewRouter.indexOfSelectedItem)
}
func testNotication(notification: NSNotification){
print("Found Combo ID \(notification.object)")
}
func addComboxValue(myVal:[String],myObj:AnyObject){
let myValno: Int = myVal.count
for var i = 0; i < myValno; ++i{
myObj.addItemWithObjectValue(myVal[i])
}
}
}
You need to define a delegate for the combobox that implements the NSComboBoxDelegate protocol, and then use the comboBoxSelectionDidChange(_:) method.
The easiest method is for your NewProjectSetup class to implement the delegate, as in:
class NewProjectSetup: NSViewController, NSComboBoxDelegate { ... etc
Then in viewDidLoad, also include:
self.projNewRouter.delegate = self
// self (ie. NewProjectSetup) implements NSComboBoxDelegate
And then you can pick up the change in:
func comboBoxSelectionDidChange(notification: NSNotification) {
print("Woohoo, it changed")
}
Related
I created an outlet in ViewController class and I'd like to modify it.
In the ViewController.swift file I have
import Cocoa
class ViewController: NSViewController {
#IBOutlet var LabelText: NSTextFieldCell?
override func viewDidLoad() {
super.viewDidLoad()
}
//other things
}
I'd like to change the background color of the label. How can I do that from AppDelegate?
At first I thought I could solve this problem using a function in ViewController and calling it in AppDelegate
func changeBackground() {
LabelText.textColor = NSColor.red
}
But soon I realised that it wasn't possible unless I used a static function. Then I tried to modify the code in ViewController like that
static func changeBackground() {
LabelText.textColor = NSColor.red
}
and call this function in AppDelegate like that
ViewController.changeBackground()
In this way I can access to changeBackground() function from AppDelegate, but in ViewController it gives me an error: Instance member 'LabelText' cannot be used on type 'ViewController'
I understood that this cannot be possible because somehow I'm calling "LabelText" before it's initialised (or something like that).
I don't know much about Swift and I'm trying to understand how it works. I've been searching for the answer to my question for hours, but still I don't know how to solve this.
Solution
As Rob suggested, the solution is to use NotificationCenter.
A useful link to understand how it works: https://www.appypie.com/notification-center-how-to-swift
Anyway, here how I modified the code.
In ViewController:
class ViewController: NSViewController {
#IBOutlet var label: NSTextFieldCell!
let didReceiveData = Notification.Name("didReceiveData")
override func viewDidLoad() {
NotificationCenter.default.addObserver(self, selector: #selector(onDidReceiveData(_:)), name: didReceiveData, object: nil)
super.viewDidLoad()
}
#objc func onDidReceiveData(_ notification: Notification) {
label.textColor = NSColor.red
}
}
And then, in AppDelegate:
let didReceiveData = Notification.Name("didReceiveData")
NotificationCenter.default.post(name: didReceiveData, object: nil)
I want to prevent certain toolbar items from being removed by the user. They should still be movable, just not removable.
I tried creating a custom subclass of NSToolbar with a custom removeItem(at:) implementation, but it seems this method is not even called if the user drags an item out of the toolbar in the customization palette.
The delegate also doesn't seem to expose functionality for this.
How can I disable removal of certain NSToolbarItems?
I am not sure if you can prevent it from being removed but you can implement the optional toolbarDidRemoveItem method and insert the item that you don't want it to be removed back:
import Cocoa
class WindowController: NSWindowController, NSToolbarDelegate {
#IBOutlet weak var toolbar: Toolbar!
override func windowDidLoad() {
super.windowDidLoad()
toolbar.delegate = self
}
func toolbarDidRemoveItem(_ notification: Notification) {
if let itemIdentifier = (notification.userInfo?["item"] as? NSToolbarItem)?.itemIdentifier,
itemIdentifier.rawValue == "NSToolbarShowColorsItem" {
toolbar.insertItem(withItemIdentifier: itemIdentifier, at: 0)
}
}
}
Since it is not super critical if they are removed in case a private API call would stop working, I opted for the private API solution.
extension NSToolbarItem {
func setIsUserRemovable(_ flag: Bool) {
let selector = Selector(("_setIsUserRemovable:"))
if responds(to: selector) {
perform(selector, with: flag)
}
}
}
This works exactly as advertised.
Is it possible to use a UISegmentedControl with 3 segments as if it was a three-way UISwitch? I tried to use one as a currency selector in the settings section of my app with no luck, it keeps reseting to the first segment when I switch views and that creates a big mess.
I proceeded like that:
IBAction func currencySelection(_ sender: Any) {
switch segmentedControl.selectedSegmentIndex {
case 0:
WalletViewController.currencyUSD = true
WalletViewController.currencyEUR = false
WalletViewController.currencyGBP = false
MainViewController().refreshPrices()
print(0)
case 1:
WalletViewController.currencyUSD = false
WalletViewController.currencyEUR = true
WalletViewController.currencyGBP = false
MainViewController().refreshPrices()
print(1)
case 2:
WalletViewController.currencyUSD = false
WalletViewController.currencyEUR = false
WalletViewController.currencyGBP = true
MainViewController().refreshPrices()
print(2)
default:
break
}
}
The UISegmentedControl is implemented in the
SettingsViewController of the app to choose between currencies to
display in the MainViewController.
(Taken from a comment in #pacification's answer.)
This was the missing piece I was looking for. It provides a lot of context.
TL;DR;
Yes, you can use a three segment UISegmentedControl as a three-way switch. The only real requirement is that you can have only one value or state selected.
But I wasn't grasping why your code referred to two view controllers and some of switching views resulting in resetting the segment. One very good way to do what you want is to:
Have MainViewController present SettingsViewController. Presenting it modally means the user is only doing one thing at a time. When they are making setting changes, you do not want them adding new currency values.
Create a delegate protocol in SettingsViewController and make MainViewController conform to it. This tightly-couples changes made to the settings to the view controller interested in what those changes are.
Here's a template for what I'm talking about:
SettingsViewController:
protocol SettingsVCDelegate {
func currencyChanged(sender: SettingsViewController)
}
class SettingsViewController : UIViewController {
var delegate:SettingsVCDelegate! = nil
var currency:Int = 0
#IBAction func valueChanged(_ sender: UISegmentedControl) {
currency = sender.selectSegmentIndex
delegate.currencyChanged(sender:self)
}
}
MainViewController:
class MainViewController: UIViewController, SettingsVCDelegate {
var currency:Int = 0
let settingsVC = SettingsViewController()
override func viewDidLoad() {
super.viewDidLoad()
settingsVC.delegate = self
}
func presentSettings() {
present(settingsVC, animated: true, completion: nil)
}
func currencyChanged(sender:SettingsViewController) {
currency = sender.currency
}
}
You can also create an enum of type Int to make your code more readable, naming each value as currencyUSD, currencyEUR, and currencyGBP. I'll leave that to you as a learning exercise.
it keeps reseting to the first segment when I switch views
yes, it is. to avoid this situation you should set the correct switch value to the segmentedControl.selectedSegmentIndex every time when you load your view with UISegmentedControl.
UPD
Ok, the behavior of MainViewController can be similar to this:
final class MainViewController: UIViewController {
private var savedValue = 0
override func viewDidLoad() {
super.viewDidLoad()
}
func openSettingsController() {
let viewController = SettingsController.instantiate() // simplify code a bit. use the full controller initialization
viewController.configure(value: savedValue, onValueChanged: { [unowned self] value in
self.savedValue = value
})
navigationController?.pushViewController(viewController, animated: true)
}
}
And the SettingsViewController:
final class SettingsViewController: UIViewController {
#IBOutlet weak var segmentedControl: UISegmentedControl!
private var value: Int = 0
var onValueChanged: ((Int) -> Void)?
func configure(value: Int, onValueChanged: #escaping ((Int) -> Void)) {
self.value = value
self.onValueChanged = onValueChanged
}
override func viewDidLoad() {
super.viewDidLoad()
segmentedControl.selectedSegmentIndex = value
}
#IBAction func valueChanged(_ sender: UISegmentedControl) {
onValueChanged?(sender.selectedSegmentIndex)
}
}
The main idea that you should keep your selected value if you moving from SettingsViewController. For this thing you can create closure
var onValueChanged: ((Int) -> Void)?
that pass back to MainViewController the selected UISegmentedControl value. And in future when you will open the SettingsViewController again you just configure() this value and set it to UI.
How can I write this so that it updates the variable when the user finishes using the field (for Cocoa?). The aim is to allow the user to specify a custom IP address for the TV's location on the network.
import Cocoa
import Alamofire
class ViewController: NSViewController, NSTextFieldDelegate {
#IBAction func MenuButton(_ sender: NSButtonCell) {
triggerRemoteControl(irccc: "AAAAAQAAAAEAAABgAw==")
}
#IBAction func ReturnButton(_ sender: NSButton) {
triggerRemoteControl(irccc: "AAAAAgAAAJcAAAAjAw==")
}
…
#IBOutlet var IPField: NSTextField! // [A] Set by the user
…
func triggerRemoteControl(irccc: String) {
Alamofire.request(IPField, // [B] Goes here when it's updated.
method: .post,
parameters: ["parameter" : "value"],
encoding: SOAPEncoding(service: "urn:schemas-sony-com:service:IRCC:1",
action: "X_SendIRCC", IRCCC: irccc)).responseString { response in
print(response)
}
}
}
— UPDATE
I tried declaring a variable:
var IPString: String
and then (I set the textField's delegate to ViewController, and placed this function inside):
override func controlTextDidEndEditing(_ obj: Notification){
let IPString = IPField.stringValue
}
Even using the "-> String" and return notation still has it complaining about unused variables. I obviously don't know my Syntax well enough.
Complier also complains about not the ViewController not being initialised.
What you need is to override the func controlTextDidEndEditing(_ obj: Notification) function
You should take a look at:
object (property of obj) - sometimes you would like to know which object sent you the end editing action.
userInfo (property of obj) - contains a "NSTextMovement" key, which allows you to define how the user did end the editing.
override func controlTextDidEndEditing(_ obj: Notification){
let IPString = IPField.stringValue
}
Here, you're creating new constant. What you want is to set this value into your class variable, so you should make IPString = IPField.stringValue
But it's not quite correct, because func controlTextDidEndEditing(_ obj: Notification) could be called from other objects, so first you should check if obj notification contain object which send it with guard, for example.
guard let object = obj.object else {
return
}
Then check if object is your IPField with identity operators
guard object === IPField else {
return
}
And finally you can assign your field value to your IPString var
IPString = object.stringValue
Hope it will help you. Ohh and one advice from my side, you should use lower camel case naming convention for you variables.
I have a Cocoa Touch Framework named FooFramework.
Within it, I want to manage the move up on the Y axis for selected views when the keyboard shows. I created a KeyboardManager class. Here's how it looks:
import UIKit
public class KeyboardManager {
var notifyFromObject: Any?
var observer: Any
public var viewsToPushUp: [UIView] = []
public init(observer: Any, viewsToPushUp: [UIView], notifyFromObject: Any? = nil) {
self.observer = observer
self.notifyFromObject = notifyFromObject
self.viewsToPushUp = viewsToPushUp
}
public func pushViewsUpWhenKeyboardWillShow(){
let notificationCenter = NotificationCenter.default
print(self)
notificationCenter.addObserver(self.observer, selector: #selector(FooFramework.KeyboardManager.pushViewsUp), name: NSNotification.Name.UIKeyboardWillShow, object: notifyFromObject)
}
#objc public func pushViewsUp(notification: NSNotification) {
if let keyboardRectValue = (notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue {
let keyboardHeight = keyboardRectValue.height
for view in viewsToPushUp {
view.frame.origin.y -= keyboardHeight
}
}
}
}
Then, I import this FooFramework in an iOS app named Bar. To test the FooFramework, I want to push up a UITextField. Here's the code:
import UIKit
import FooFramework
class ViewController: UIViewController {
#IBOutlet weak var textField: UITextField!
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
let kb = KeyboardManager(observer: self, viewsToPushUp: [textField], notifyFromObject: nil)
kb.pushViewsUpWhenKeyboardWillShow()
}
func pushViewsUp(notification: NSNotification) {
print("This should not be printed")
}
}
My problem is that This should not be printed appears in the console and the pushViewsUp method from the KeyboardManager never gets called. Even though I used a fully qualified name for the selector, it insists on using the pushViewsUp from the ViewController. This is driving me nuts.
If I remove pushViewsUp from the ViewController, I get the following error:
Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[Bar.ViewController pushViewsUpWithNotification:]: unrecognized selector sent to instance 0x7fc540702d80'
What do I need to do so the selector properly points to FooFramework.KeyboardManager.pushViewsUp?
I believe you need to use self instead of self.observer for the observer in the addObserver function.
Also you need to declare the kb variable outside the scope of the function in order for the manager to detect the notification.
Example:
import UIKit
import FooFramework
class ViewController: UIViewController {
#IBOutlet weak var textField: UITextField!
var kb: KeyboardManager?
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
kb = KeyboardManager(observer: self, viewsToPushUp: [textField], notifyFromObject: nil)
kb?.pushViewsUpWhenKeyboardWillShow()
}
}
KeyboardManager changes:
public func pushViewsUpWhenKeyboardWillShow() {
let notificationCenter = NotificationCenter.default
print(self)
notificationCenter.addObserver(self,
selector: #selector(FooFramework.KeyboardManager.pushViewsUp),
name: NSNotification.Name.UIKeyboardWillShow,
object: notifyFromObject)
}
Other than what Justin has suggested which is all correct, there are a few more things to consider before you fully solve the problem.
KeyBoardManager class instance itself is going to observe the keyboardWillMoveUp notification so your
var observer: Any
within it is unnecessary. You should remove that.
I would also put the addObserver part right in the init of KeyBoardManager class itself so that this extra call pushViewsUpWhenKeyboardWillShow() can be avoided which seems to be doing nothing but that. Since the KeyBoardManager class is supposed to be doing only this, I don't see why adding observer should be another function call.
So this is how your KeyboardManager class should look:
import UIKit
public class KeyboardManager {
var notifyFromObject: Any?
public var viewsToPushUp: [UIView] = []
public init(viewsToPushUp: [UIView], notifyFromObject: Any? = nil){
self.notifyFromObject = notifyFromObject
self.viewsToPushUp = viewsToPushUp
//remember KeyboardManager itself is observing the notifications and moving the views it received from the ViewController. Hence we use self.
NotificationCenter.default.addObserver(self, selector: #selector(FooFramework.KeyboardManager.pushViewsUp), name: NSNotification.Name.UIKeyboardWillShow, object: notifyFromObject)
}
#objc public func pushViewsUp(notification: NSNotification) {
if let keyboardRectValue = (notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue {
let keyboardHeight = keyboardRectValue.height
for view in viewsToPushUp {
view.frame.origin.y -= keyboardHeight
}
}
}
}
You will also need to work with the frames properly before you get the right behavior out of this.
You should extend the lifespan of your KeyboardManagerInstance to live as long as the ViewController which has the textField is alive. You do it by declaring it as an instance variable inside the ViewController as Justin has suggested. The way you were doing it, your KeyboardManager instance is a local variable which is created and immediately released as soon as the function goes out of scope. To verify this, you can add this to your KeyboardManager class and check:
deinit {
print("KeyboardManager is perhaps dying an untimely death.")
}
Finally your ViewController class should do just this
import UIKit
import FooFramework
class ViewController: UIViewController {
#IBOutlet weak var textField: UITextField!
var kb: KeyboardManager?
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
kb = KeyboardManager(viewsToPushUp: [textField], notifyFromObject: nil)
//observe that there is no observer param in the initializer and also no "pushViewsUpWhenKeyboardWillShow" call as that behavior has already been moved to init itself.
}
}