I try to make an app, and now i shoud make some changes when screen resolution will change, but i coudn't find how to intercept this event.
Do you have any ideea how can i take that event?
The NSApplicationDidChangeScreenParametersNotification is posted when the configuration of the displays attached to the computer is changed, so
you can register for that notification, e.g. with
NSNotificationCenter.defaultCenter().addObserverForName(NSApplicationDidChangeScreenParametersNotification,
object: NSApplication.sharedApplication(),
queue: NSOperationQueue.mainQueue()) {
notification -> Void in
println("screen parameters changed")
}
Note that there can be various reasons why this notification is
fired, e.g. a change in the dock size (as observed in Cocoa Dock fires NSApplicationDidChangeScreenParametersNotification), so you have to
"remember" the old resolution and compare it with the new resolution.
Swift 4:
The didChangeScreenParametersNotification is posted when the configuration of the displays attached to the computer is changed.
Inside the func applicationDidFinishLaunching() in AppDelegate class or func viewDidLoad() in ViewController class, insert the following code:
NotificationCenter.default.addObserver(forName: NSApplication.didChangeScreenParametersNotification,
object: NSApplication.shared,
queue: OperationQueue.main) {
notification -> Void in
print("screen parameters changed")}
I personally, used it to center the position of my application when switching between the Mac and the external screen.
Here is the updated Swift 3 code:
NotificationCenter.default.addObserver(forName: NSNotification.Name.NSApplicationDidChangeScreenParameters,
object: NSApplication.shared(),
queue: OperationQueue.main) {
notification -> Void in
print("screen parameters changed")
}
Code for Swift 5+
NotificationCenter.default.addObserver(
forName: NSNotification.Name(rawValue: "NSApplicationDidChangeScreenParametersNotification"),
object: NSApplication.shared,
queue: .main) { notification in
self.adjustUIIfNeeded()
}
Related
I'd like to save the state of Check Box, quit application, then launch macOS app again to see restored state of my Check Box. But there's no restored state in UI of my app.
What am I doing wrong?
import Cocoa
class ViewController: NSViewController {
#IBOutlet weak var tick: NSButton!
override func viewDidLoad() {
super.viewDidLoad()
}
override func encodeRestorableState(with coder: NSCoder) {
super.encodeRestorableState(with: coder)
coder.encode(tick.state, forKey: "")
}
override func restoreState(with coder: NSCoder) {
super.restoreState(with: coder)
if let state = coder.decodeObject(forKey: "") as? NSControl.StateValue {
tick.state = state
}
}
}
To the best of my knowledge, this is the absolute minimum you need to implement custom UI state restoration of a window and/or its contents.
In this example, I have a window with a checkbox and that checkbox's state represents some custom view state that I want to restore when the app is relaunched.
The project contains a single window with a single checkbox button. The button's value is bound to the myState property of the window's content view controller. So, technically, the fact that this is a checkbox control is irrelevant; we're actually going to preserve and restore the myState property (the UI takes care of itself).
To make this work, the window's restorable property is set to true (in the window object inspector) and the window is assigned an identifier ("PersistentWindow"). NSWindow is subclassed (PersistentWindow) and the subclass implements the restorableStateKeyPaths property. This property lists the custom properties to be preserved/restored.
Note: if you can define your UI state restoration in terms of a list of key-value compliant property paths, that is (by far) the simplest solution. If not, you must implement encodeRestorableState / restoreState and are responsible for calling invalidateRestorableState.
Here's the custom window class:
class PersistentWindow: NSWindow {
// Custom subclass of window the perserves/restores UI state
// The simple way to preserve and restore state information is to just declare the key-value paths
// of the properties you want preserved/restored; Cocoa does the rest
override class var restorableStateKeyPaths: [String] {
return [ "self.contentViewController.myState" ]
}
// Alternatively, if you have complex UI state, you can implement these methods
// override func encodeRestorableState(with coder: NSCoder) {
// // optional method to encode special/complex view state here
// }
//
// override func restoreState(with coder: NSCoder) {
// // companion method to decode special/complex view state
// }
}
And here's the (relevant portion) of the content view controller
class ViewController: NSViewController {
#objc var myState : Bool = false
blah, blah, blah
}
(I built this as a Cocoa app project, which I could upload if someone tells me where I could upload it to.)
Actually you don't have to go through restorableStateKeyPaths / KVO / KVC if you don't want to.
I was stuck in the same state as you with the encodeRestorableState() & restoreState() methods not being called but found out what was missing.
In System Preferences > General, make sure "Close windows when quitting an app" is unchecked.
Make sure that the NSWindow containing your view has "Restorable" behavior enabled in IB.
Make sure that your NSViewController has a "Restoration ID" set.
Your NSViewController won't be encoded unless you call invalidateRestorableState(). You need to call this each time there's a state in your NSViewController that changes and that you want to have saved.
When no state changes in the NSViewController after having restored it, its state would not be encoded again when closing the app. Which would cause the custom states to not be restored when relaunching the app. The simplest way I found is to also call invalidateRestorableState() in viewDidLoad(), so that state is always saved.
After doing all that, I didn't even have to additionally implement NSApplicationDelegate or NSWindowRestoration protocol methods. So the state restoration of the NSViewController is pretty self-contained. Only external property is restorable NSWindow.
After losing a couple of hours of my life to this problem I finally got it working. Some of the information in the other answers was helpful, some was missing, some was not necessary.
Here is my minimal example based on a new Xcode 13 project:
in AppDelegate add (this is missing in the other examples):
func applicationSupportsSecureRestorableState(_ app: NSApplication) -> Bool { return true }
in ViewController add:
#objc var myState : Bool = false
override class var restorableStateKeyPaths: [String] {
return [ "myState" ]
}
set up some UI and bind it to myState to see what is going on
make sure System Preferences > General > "Close windows when quitting an app" is unchecked
Things that I did not need to do:
create a custom window subclass
set a custom restoration id
it worked fine just with Xcode start/stop
I am simply trying to get undo working for the actions a user performs in my app. By default, any text editing the user does has the benefit of undo, but any actions that are done otherwise (from my code) does not.
I can see the documentation explains that I need to get an instance of NSUndoManager and call registerUndoWithTarget, but I am stumped with the first step: getting the undoManager from within my ViewController. Since ViewController is a UIResponder, I tried this:
if let undoManager = self.undoManager {
undoManager.registerUndoWithTarget(self, selector: Selector("removeLatestEntry:"), object: "test")
}
Since that binding returns nil, I thought maybe the ViewController doesn't have the undoManager, so I looked for it in the window:
if let window = NSApplication.sharedApplication().mainWindow {
if let undoManager = window.undoManager {
undoManager.registerUndoWithTarget(self, selector: Selector("removeLatestEntry:"), object: "test")
}
}
Alas, the window binding also returns nil. Sorry, I am very new to this. Can anyone point me in the right direction? Am I supposed to implement my own undoManager or something? There is clearly an undoManager somewhere because anything a user does manually in my textField is getting undo behavior. It seems like this would be a singleton that I could access easily from a ViewController.
--
Edit: BTW, the code above was placed in viewDidLoad and removeLatestEntry is just a function in my ViewController that takes a string and prints it at this point.
To use undoManager, the ViewController needs to be first responder. So:
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
becomeFirstResponder()
}
Then, from wherever your action is defined that needs to be reversed, you register your undo and pass it whatever it needs to undo that action. So in my case:
func addEntry(activity: String) {
// some other stuff…
undoManager!.registerUndoWithTarget(self, selector: Selector("removeLatestEntry:"), object: activity)
}
I've recently started working on some test projects to get the feel for OS X development with Xcode. I come from Windows, so I might not be making much sense here.
How would I subscribe to certain "events" in Swift? I have just learned how to connect actions to UI objects. For example, I can now click a button, and change the text of a label programatically. However, and this may just be a case of lack of knowledge on my part - I am not able to find a way to subscribe to a TextField's "Text Changed" event.
Let's say that I have a TextField, and when I change the text at runtime (i.e. type something), I want to do something in the textChanged event for that particular TextField.
Is there even such a thing as a TextChanged event in OS X development?
Update
I am now using the following code:
import Cocoa
class ViewController: NSViewController {
class textField:NSTextField, NSTextFieldDelegate
{
override func awakeFromNib() {
delegate = self;
}
override func controlTextDidChange(obj: NSNotification)
{
println("Text changed.")
}
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
override var representedObject: AnyObject? {
didSet {
// Update the view, if already loaded.
}
}
}
And I have added a ClassName to the TextField control in the Identity Inspector, but it isn't responding to the text changing. The message given is:
Failed to connect (textField) outlet from
(Xcode_Action_Basics.ViewController) to (NSTextField): missing setter
or instance variable
I just googled that error and came across this page: Failed to connect (storyboard) outlet from (NSApplication) to (NSNibExternalObjectPlaceholder) error in Cocoa and storyboard which states that this is a known issue in Xcode and that it does not mean there is a problem with your code - but I'm not so sure about that, because the code isn't working. Not sure if I've missed out on something.
Create a class that implements the protocol NSTextFieldDelegate like
class MyTextField:NSTextField, NSTextFieldDelegate {
override func awakeFromNib() {
delegate = self // tell that we care for ourselfs
}
override func controlTextDidChange(obj: NSNotification) {
// .... handle change, there are a lot of other similar methods. See help
}
}
In IB assign this class here:
I got very strange behavior when reloading NSTableView data inside notification observer.
class MainWindowController: NSWindowController, NSTableViewDataSource, NSTableViewDelegate
{
var data: String[] = []
#IBOutlet var filesTableView: NSTableView!
override func awakeFromNib()
{
super.awakeFromNib()
NSNotificationCenter.defaultCenter().addObserver(self, selector: "droppedFiles:", name: DroppedFilesNotification.notificationName, object: nil)
}
func droppedFiles(notification: NSNotification!)
{
data += ["123"]
println(data.count)
filesTableView.reloadData()
}
func numberOfRowsInTableView(tableView: NSTableView!) -> Int
{
return data.count
}
#IBAction func crazyTest(AnyObject)
{
NSNotificationCenter.defaultCenter().postNotificationName(DroppedFilesNotification.notificationName, object: self, userInfo: [DroppedFilesNotification.fileNamesParameterName: ["123"]])
}
}
First call of crazyTest function displays:
1
Seconds call of crazyTest function displays:
2
3
4
Third call of crazyTest function displays numbers 5-13.
If we would remove filesTableView.reloadData() from droppedFiles function then all works fine except table view isn't updated. Any idea why this happens and how to reload table view there?
EDIT:
Also, there is no issue in case calling droppedFiles function directly instead of using NSNotificationCenter. But I'd prefer to use notification center in my application.
Thanks ahead.
If this is a view-based table view which (perhaps implicitly) loads its views from NIBs, then its awakeFromNib method will get called each time the NIB is loaded. From here:
Note: Calling makeViewWithIdentifier:owner: causes awakeFromNib to be
called multiple times in your app. This is because
makeViewWithIdentifier:owner: loads a NIB with the passed-in owner,
and the owner also receives an awakeFromNib call, even though it’s
already awake.
In your case, you're registering for the notification each time. So, you're registering for it many times over and you receive the notification once for each time you registered.
You are not removing the observer. My guess is that you are going into that view controller multiple times and therefore it is registered for the same notification multiple times. Therefore, when the notifications is triggered, the callback gets called multiple times.
I have made a custom NSView and have implemented the keyDown: method. However, when I press keys the method is never called. Do I have to register to receive those events? fyi, I am making a document based application and can handle this code anywhere (doesn't have to be in this view). What is the best place to do this in a document based application such that the event will occur throughout the entire application?
You need to override -acceptsFirstResponder to return YES.
In Swift:
class MDView: NSView {
override var acceptsFirstResponder: Bool { return true }
}