There are lots of related answers about using menuWillOpen. They all explain that one needs to set the menu's delegate first.
This is easy when I have just one target, like a Preferences window or the main application.
But what if I have a document based app, and I need to have the active document handle menuWillOpen? Then the delegate isn't a constant any more.
What's the proper way to handle this? Do I have to set the delegate to a single object (like the AppDelegate) and then forward the call to the active view controller (but how is that done correctly)? Or is there some other elegant way?
I came up with this code which appears to work:
// This is in my AppDelegate class, and the NSMenu's delegate points to it:
- (void)menuWillOpen:(NSMenu *)menu {
// Forward to active document controller
NSWindow *mainWindow = [NSApplication sharedApplication].mainWindow;
NSResponder *r = mainWindow.firstResponder;
while (r) {
if ([r respondsToSelector:_cmd]) {
[(id<NSMenuDelegate>)r menuWillOpen:menu];
return;
}
r = r.nextResponder;
}
}
It assumes that a controller down the responder chain implements menuWillOpen:
Related
I have a custom UIView subclass and want to detect when its ancestor is in focus. But this class itself cannot be focused.
Basically, I want to do something similar to UIImageView when adjustsImageWhenAncestorFocused is set to true.
I'm hoping for a solution that doesn't require the ancestor to communicate when focus changes.
You could implement the didUpdateFocusInContext and check if the target view is your ancestor:
override func didUpdateFocusInContext(context: UIFocusUpdateContext, withAnimationCoordinator coordinator: UIFocusAnimationCoordinator)
{
if let target = context.nextFocusedView
where self.isDescendantOfView(target)
{
// one of your ancestors has received focus
}
}
We can't use didUpdateFocus(in:with:), because it isn't called for all views of hierarchy, from the documentation:
the focus engine calls this method on all focus environments that contain either the previously focused view, the next focused view, or both
So if the view return false for canBecomeFocused, this method can't be called on it.
The adequate way is to observe UIFocusSystem.didUpdateNotification, if you're using Combine it's something like this:
NotificationCenter.default.publisher(for: UIFocusSystem.didUpdateNotification).sink { [weak self] notification in
guard let context = notification.userInfo?[UIFocusSystem.focusUpdateContextUserInfoKey] as? UIFocusUpdateContext,
let next = context.nextFocusedView, self?.isDescendant(of: next) ?? false else {
print("is NOT descendant")
return
}
print("is descendant")
}.store(in: &cancelBag)
In a test Swift project, I am subclassing NSWindowController. My NSWindowController subclass is designed to work with a particular Nib file. It is desirable, then, that when my window controller is initialized, the nib file is automatically loaded by the window controller instance. In Objective-C, this was achieved by doing:
#implementation MyWindowController
- (id)init {
self = [super initWithWindowNibName:"MyWindowNib"]
if (self) {
// whatever
}
return self
}
#end
Now, in Swift this is not possible: init() cannot call super.init(windowNibName:), because the later is declared not as a designated initializer, but as a convenience one by NSWindowController.
How can this be done in Swift? I don't see a strightforward way of doing it.
P.S.: I have seen other questions regarding this topic, but, as long as I've been able to understand, the solutions all point to initialize the Window Controller by calling init(windowNibName:). Please note that this is not the desired beheaviour. The Window Controller should be initialized with init(), and it should be the Window Controller itself who "picks up" its Nib file and loads it.
If you use the init() just to call super.init(windowNibName:), you could instead just override the windowNibName variable.
override var windowNibName: String {
get {
return "MyWindowNib"
}
}
Then there should be no need to mess with the initializers.
You can create your own convenience initializer instead:
override convenience init() {
self.init(windowNibName: "MyWindowNib")
}
You should instead opt in to replacing all designated initializers in your subclass, simply delegating to super where appropriate. Confer https://stackoverflow.com/a/24220904/1460929
How can I use IKScannerDeviceView to scan a document inside of my app?
I tried adding an IKScannerDeviceView into my view through IB and setting its delegate to my app delegate (which implements the IKScannerDeviceViewDelegate), but when I run the app I get a view with the buttons Show Details and Scan, and only Show Details is enabled and when I click it nothing happens.
I have a scanner plugged in and I can scan through Image Capture, but not through my app.
Does anybody have a good tutorial on how to use it?
I was finally able to figure out how to use IKScannerDeviceView.
Your class must implement the following delegates:
IKScannerDeviceViewDelegate, ICScannerDeviceDelegate, ICDeviceBrowserDelegate
and you need to have an IKScannerDeviceView in your window, with its delegate set to the class implementing IKScannerDeviceViewDelegate
To start using it, you must create an ICDeviceBrowser like so:
ICDeviceBrowser *mDeviceBrowser = [[ICDeviceBrowser alloc] init];
mDeviceBrowser.delegate = self;
mDeviceBrowser.browsedDeviceTypeMask = ICDeviceLocationTypeMaskLocal|ICDeviceLocationTypeMaskRemote|ICDeviceTypeMaskScanner;
[mDeviceBrowser start];
Then implement the delegate methods in a manner similar to this:
- (void)scannerDeviceDidBecomeAvailable:(ICScannerDevice*)scanner;
{
[scanner requestOpenSession];
}
- (void)deviceBrowser:(ICDeviceBrowser*)browser didAddDevice:(ICDevice*)addedDevice moreComing:(BOOL)moreComing
{
if ( (addedDevice.type & ICDeviceTypeMaskScanner) == ICDeviceTypeScanner )
{
[scannerView setScannerDevice:(ICScannerDevice*)addedDevice];
}
}
-(void)didRemoveDevice:(ICDevice*)removedDevice
{
[removedDevice requestCloseSession];
}
Then if all goes right, your IKScannerDeviceView will be able to interact with your scanner!
I've read Apple's Pasteboard Programming Guide, but it doesn't answer a particular question I have.
I'm trying to write a Cocoa application (for OS X, not iOS) that will keep track of everything that is written to the general pasteboard (so, whenever any application copies and pastes, but not, say, drags-and-drops, which also makes use of NSPasteboard). I could (almost) accomplish this by basically polling the general pasteboard on a background thread constantly, and checking changeCount. Of course, doing this would make me feel very dirty on the inside.
My question is, is there a way to ask the Pasteboard server to notify me through some sort of callback any time a change is made to the general pasteboard? I couldn't find anything in the NSPasteboard class reference, but I'm hoping it lurks somewhere else.
Another way I could imagine accomplishing this is if there was a way to swap out the general pasteboard implementation with a subclass of NSPasteboard that I could define myself to issue a callback. Maybe something like this is possible?
I would greatly prefer if this were possible with public, App Store-legal APIs, but if using a private API is necessary, I'll take that too.
Thanks!
Unfortunately the only available method is by polling (booo!). There are no notifications and there's nothing to observe for changed pasteboard contents. Check out Apple's ClipboardViewer sample code to see how they deal with inspecting the clipboard. Add a (hopefully not overzealous) timer to keep checking for differences and you've got a basic (if clunky) solution that should be App-Store-Friendly.
File an enhancement request at bugreporter.apple.com to request notifications or some other callback. Unfortunately it wouldn't help you until the next major OS release at the earliest but for now it's polling until we all ask them to give us something better.
There was once a post on a mailing list where the decision against a notification api was described. I can't find it right now though. The bottom line was that probably too many applications would register for that api even though they really wouldn't need to. If you then copy something the whole system goes through the new clipboard content like crazy, creating lots of work for the computer. So i don't think they'll change that behavior anytime soon. The whole NSPasteboard API is internally built around using the changeCount, too. So even your custom subclass of NSPasteboard would still have to keep polling.
If you really want to check if the pasteboard changed, just keep observing the changeCount very half second. Comparing integers is really fast so there's really no performance issue here.
Based on answer provided by Joshua I came up with similar implementation but in swift, here is the link to its gist: PasteboardWatcher.swift
Code snippet from same:
class PasteboardWatcher : NSObject {
// assigning a pasteboard object
private let pasteboard = NSPasteboard.generalPasteboard()
// to keep track of count of objects currently copied
// also helps in determining if a new object is copied
private var changeCount : Int
// used to perform polling to identify if url with desired kind is copied
private var timer: NSTimer?
// the delegate which will be notified when desired link is copied
weak var delegate: PasteboardWatcherDelegate?
// the kinds of files for which if url is copied the delegate is notified
private let fileKinds : [String]
/// initializer which should be used to initialize object of this class
/// - Parameter fileKinds: an array containing the desired file kinds
init(fileKinds: [String]) {
// assigning current pasteboard changeCount so that it can be compared later to identify changes
changeCount = pasteboard.changeCount
// assigning passed desired file kinds to respective instance variable
self.fileKinds = fileKinds
super.init()
}
/// starts polling to identify if url with desired kind is copied
/// - Note: uses an NSTimer for polling
func startPolling () {
// setup and start of timer
timer = NSTimer.scheduledTimerWithTimeInterval(2, target: self, selector: Selector("checkForChangesInPasteboard"), userInfo: nil, repeats: true)
}
/// method invoked continuously by timer
/// - Note: To keep this method as private I referred this answer at stackoverflow - [Swift - NSTimer does not invoke a private func as selector](http://stackoverflow.com/a/30947182/217586)
#objc private func checkForChangesInPasteboard() {
// check if there is any new item copied
// also check if kind of copied item is string
if let copiedString = pasteboard.stringForType(NSPasteboardTypeString) where pasteboard.changeCount != changeCount {
// obtain url from copied link if its path extension is one of the desired extensions
if let fileUrl = NSURL(string: copiedString) where self.fileKinds.contains(fileUrl.pathExtension!){
// invoke appropriate method on delegate
self.delegate?.newlyCopiedUrlObtained(copiedUrl: fileUrl)
}
// assign new change count to instance variable for later comparison
changeCount = pasteboard.changeCount
}
}
}
Note: in the shared code I am trying to identify if user has copied a
file url or not, the provided code can easily be modified for other general
purposes.
For those who need simplified version of code snippet that gets the job done in Swift 5.7,
it just works (base on #Devarshi code):
func watch(using closure: #escaping (_ copiedString: String) -> Void) {
let pasteboard = NSPasteboard.general
var changeCount = NSPasteboard.general.changeCount
Timer.scheduledTimer(withTimeInterval: 1.0, repeats: true) { _ in
guard let copiedString = pasteboard.string(forType: .string),
pasteboard.changeCount != changeCount else { return }
defer {
changeCount = pasteboard.changeCount
}
closure(copiedString)
}
}
how to use is as below:
watch {
print("detected : \($0)")
}
then if you attempt copy any text in your pasteboard, it will watch and print out to the console like below..
detected : your copied message in pasteboard
detected : your copied message in pasteboard
in case, full code sample for how to use it for example in SwiftUI:
import SwiftUI
#main
struct TestApp: App {
var body: some Scene {
WindowGroup {
ContentView()
.onAppear {
watch {
print("detect : \($0)")
}
}
}
}
func watch(using closure: #escaping (_ copiedString: String) -> Void) {
let pasteboard = NSPasteboard.general
var changeCount = NSPasteboard.general.changeCount
Timer.scheduledTimer(withTimeInterval: 1.0, repeats: true) { _ in
guard let copiedString = pasteboard.string(forType: .string),
pasteboard.changeCount != changeCount else { return }
defer {
changeCount = pasteboard.changeCount
}
closure(copiedString)
}
}
}
It's not necessary to poll. Pasteboard would generally only be changed by the current view is inactive or does not have focus. Pasteboard has a counter that is incremented when contents change. When window regains focus (windowDidBecomeKey), check if changeCount has changed then process accordingly.
This does not capture every change, but lets your application respond if the Pasteboard is different when it becomes active.
In Swift...
var pasteboardChangeCount = NSPasteboard.general().changeCount
func windowDidBecomeKey(_ notification: Notification)
{ Swift.print("windowDidBecomeKey")
if pasteboardChangeCount != NSPasteboard.general().changeCount
{ viewController.checkPasteboard()
pasteboardChangeCount = NSPasteboard.general().changeCount
}
}
I have a solution for more strict case: detecting when your content in NSPasteboard was replaced by something else.
If you create a class that conforms to NSPasteboardWriting and pass it to -writeObjects: along with the actual content, NSPasteboard will retain this object until its content is replaced. If there are no other strong references to this object, it get deallocated.
Deallocation of this object is the moment when new NSPasteboard got new content.
I didin't completely understand the delegate mechanism in monotouch. Can anyone help me to understand this concept?
The question is simple. I'll try to map what I've done in Objective C in Monotouch.
For example, suppose I've creating a UIPopoverController in Objective C inside MyController. In Objective C the code is the following:
#interface MyController : UIViewController <UIPopoverControllerDelegate> {
// ...
}
// ...
#end
Inside MyController I can istantiate a UIPopoverController like the following:
UIPopoverController *popover = // ...
popover.delegate = self;
and finally methods used in the delegate.
So, what about Monotouch?
Through this code I can istantiate the UIPopoverController inside MyController class that extends UIViewController inside a specific TouchUpInside event handler:
popover = new UIPopoverController(new CustomController());
popover.PopoverContentSize = new SizeF(200f, 200f);
popover.PresentFromRect(button.Frame, containerForButtonView, UIPopoverArrowDirection.Left, true);
P.S. An important aspect is to put popover reference as a member class and not as a local variable inside the handler because the monotouch GC works well!!!
Thank you in advance.
This really has more to do with C# than MonoTouch itself. In MonoTouch, UIPopoverControllerDelegate is a class, and C# doesn't allow multiple inheritance, so you can't translate code one to one with Obj-C. There's an easier way out though (code below compiles, but obviously doesn't work):
public class MyController: UIViewController {
public void mymethod(){
var popover = new UIPopoverController();
popover.DidDismiss += HandlePopoverDidDismiss;
popover.PopoverContentSize = new SizeF(200f, 200f);
popover.PresentFromRect(button.Frame, containerForButtonView, UIPopoverArrowDirection.Left, true);
}
void HandlePopoverDidDismiss (object sender, EventArgs e)
{
Console.WriteLine("Working!");
}
}
}
As you can see, you can add an event handler to to the DidDismiss event in the popover, which will do what you want. In general, all events that in Obj-C are handled by the delegate in all controls can be used this way. You can also write the method inline, like this:
popover.DidDismiss += delegate {
//dosomething
};
Hope this is what you're looking for.
This doesn't answer your question specific to your UIPopovercontroller I think you will find this link from the Monotouch Docs useful. It explains the differences between Objective-C delegates and C# delegates with relation to Monotouch. With regards to your specific problem, I havent got time to whip up a quick test case to understand it fully but figured I'd post that link so you've got something to read in the mean time!