I want to set key equivalent " "(space) without any modifiers for NSMenuItem (in App Main Menu).
As follows from documentation:
For example, in an application that plays media, the Play command may be mapped to just “ ” (space), without the command key. You can do this with the following code:
[menuItem setKeyEquivalent:#" "];
[menuItem setKeyEquivalentModifierMask:0];
Key Equivalent sets successfully, but it don't work. When I press "Space" key without modifiers nothing happens, but it's works when i press "Space" with "Fn" modifier key.
I need to use "Space" without modifiers. Any help please!
This is a tricky question. Like many answers suggest, intercepting the event at the application or window level is a solid way to force the menu item to work. At the same time it is likely to break other things, for example, if you have a focused NSTextField or NSButton you'd want them to consume the event, not the menu item. This might also fail if the user redefines the key equivalent for that menu item in system preferences, i.e., changes Space to P.
The fact that you're using the space key equivalent with the menu item makes things even trickier. Space is one of the special UI event characters, along with the arrow keys and a few others, that the AppKit treats differently and in certain cases will consume before it propagates up to the main menu.
So, there are two things to keep in mind. First, is the standard responder chain:
NSApplication.sendEvent sends event to the key window.
Key window receives the event in NSWindow.sendEvent, determines if it is a key event and invokes performKeyEquivalent on self.
performKeyEquivalent sends it to the current window's firstResponder.
If the responder doesn't consume it, the event gets recursively sent upwards to the nextResponder.
performKeyEquivalent returns true if one of the responders consumes the event, false otherwise.
Now, the second and tricky part, if the event doesn't get consumed (that is when performKeyEquivalent returns false) the window will try to process it as a special keyboard UI event – this is briefly mentioned in Cocoa Event Handling Guide:
The Cocoa event-dispatch architecture treats certain key events as commands to move control focus to a different user-interface object in a window, to simulate a mouse click on an object, to dismiss modal windows, and to make selections in objects that allow selections. This capability is called keyboard interface control. Most of the user-interface objects involved in keyboard interface control are NSControl objects, but objects that aren’t controls can participate as well.
The way this part works is pretty straightforward:
The window converts the key event in a corresponding action (selector).
It checks with the first responder if it respondsToSelector and invokes it.
If the action was invoked the event gets treated as consumed and the event propagation stops.
So, with all that in mind, you must ensure two things:
The responder chain is correctly set up.
Responders consumes only what they need and propagate events otherwise.
The first point rarely gives troubles. The second one, and this is what happens in your example, needs taking care of – the AVPlayer would typically be the first responder and consume the space key event, as well as a few others. To make this work you need to override keyUp and keyDown methods to propagate the event up the responder chain as would happen in the default NSView implementation.
// All player keyboard gestures are disabled.
override func keyDown(with event: NSEvent) {
self.nextResponder?.keyDown(with: event)
}
// All player keyboard gestures are disabled.
override func keyUp(with event: NSEvent) {
self.nextResponder?.keyUp(with: event)
}
The above forwards the event up the responder chain and it will eventually be received by main menu. There's one gotcha, if first responder is a control, like NSButton or any custom NSControl-inheriting object, it WILL consume the event. Typically you do want this to happen, but if not, for example when implementing custom controls, you can override respondsToSelector:
override func responds(to selector: Selector!) -> Bool {
if selector == #selector(performClick(_:)) { return false }
return super.responds(to: selector)
}
This will prevent the window from consuming the keyboard UI event, so the main menu can receive it instead. However, if you want to intercept ALL keyboard UI events, including when the first responder is able to consume it, you do want to override your window's or application's performKeyEquivalent, but without duplicating it as other answers suggest:
override func performKeyEquivalent(with event: NSEvent) -> Bool {
// Attempt to perform the key equivalent on the main menu first.
if NSApplication.shared.mainMenu?.performKeyEquivalent(with: event) == true { return true }
// Continue with the standard implementation if it doesn't succeed.
return super.performKeyEquivalent(with: event)
}
If you invoke performKeyEquivalent on the main menu without checking for result you might end up invoking it twice – first, manually, and second, automatically from the super implementation, if the event doesn't get consumed by the responder chain. This would be the case when AVPlayer is the first responder and keyDown and keyUp methods not overwritten.
P.S. Snippets are Swift 4, but the idea is the same! ✌️
P.P.S. There's a brilliant WWDC 2010 Session 145 – Key Event Handling in Cocoa Applications that covers this subject in depth with excellent examples. WWDC 2010-11 is no longer listed on Apple Developer Portal but the full session list can be found here.
I had the same problem. I haven't investigated very hard, but as far as I can tell, the spacebar doesn't "look" like a keyboard shortcut to Cocoa so it gets routed to -insertText:. My solution was to subclass the NSWindow, catch it as it goes up the responder chain (presumably you could subclass NSApp instead), and send it off to the menu system explicitly:
- (void)insertText:(id)insertString
{
if ([insertString isEqual:#" "]) {
NSEvent *fakeEvent = [NSEvent keyEventWithType:NSKeyDown
location:[self mouseLocationOutsideOfEventStream]
modifierFlags:0
timestamp:[[NSProcessInfo processInfo] systemUptime]
windowNumber:self.windowNumber
context:[NSGraphicsContext currentContext]
characters:#" "
charactersIgnoringModifiers:#" "
isARepeat:NO
keyCode:49];
[[NSApp mainMenu] performKeyEquivalent:fakeEvent];
} else {
[super insertText:insertString];
}
}
I have just been experiencing the same problem with a twist...
The spacebar key equivalent works fine in my app while the NSMenuItem's linked IBAction is located in the App Delegate.
If I move the IBAction into a dedicated controller it fails. All other menu item key equivalents continue to work but the spacebar does not respond (it is ok with a modifier key, but unmodified #" " will not work).
I have tried various workarounds, like linking directly to the controller vs. linking via the responder chain, to no avail. I tried the code way:
[menuItem setKeyEquivalent:#" "];
[menuItem setKeyEquivalentModifierMask:0];
and the Interface Builder way, the behaviour is the same
I have tried subclassing NSWindow, as per Justin's answer, but so far have failed to get that to work.
So for now I have surrendered and relocated this one IBAction to the App Delegate where it works. I don't regard this as a solution, just making do... perhaps it's a bug, or (more likely) I just don't understand event messaging and the responder chain well enough.
Up this post because i need to use space too but no of those solutions work for me.
So, I subclass NSApplication and use the sendEvent: selector with the justin k solution :
- (void)sendEvent:(NSEvent *)anEvent
{
[super sendEvent:anEvent];
switch ([anEvent type]) {
case NSKeyDown:
if (([anEvent keyCode] == 49) && (![anEvent isARepeat])) {
NSPoint pt; pt.x = pt.y = 0;
NSEvent *fakeEvent = [NSEvent keyEventWithType:NSKeyDown
location:pt
modifierFlags:0
timestamp:[[NSProcessInfo processInfo] systemUptime]
windowNumber: 0 // self.windowNumber
context:[NSGraphicsContext currentContext]
characters:#" "
charactersIgnoringModifiers:#" "
isARepeat:NO
keyCode:49];
[[NSApp mainMenu] performKeyEquivalent:fakeEvent];
}
break;
default:
break;
}
}
Hope it will help
Quick Swift 4-5 method:
In view controller:
// Capture space and call main menu
override func keyDown(with event: NSEvent) {
if event.keyCode == 49 && !event.isARepeat{
NSApp.mainMenu?.performKeyEquivalent(with: event)
}
super.keyDown(with: event)
}
Related
Intro
When my custom NSTextField is in "text editing mode" and the field editor has been placed in front of it as firstResponder I no longer get the keystrokes through NSTextField.keyDown(...). I understand that the keystrokes are now being routed through the field editor. Most online recommendations are to override the following method within the delegate of the custom NSTextField:
control(_:textView:doCommandBySelector:)
I have indeed overridden this method but it doesn't seem to get called? See code below:
class FocusDelegate: NSObject, NSTextFieldDelegate{
func control(control: NSControl, textView: NSTextView, doCommandBySelector commandSelector: Selector) -> Bool {
println("FocusDelegate")
if commandSelector == Selector("cancelOperation:"){
println("cancelOperation")
control.abortEditing()
return true
}
return false
}
}
The only other thing I do is set the delegate of my custom NSTextField to an instance of the class above. I have also tried placing the method above directly into the custom NSTextField class - it doesn't cause any errors but it also doesn't get called.
Questions
What am I missing above in getting the delegate call to work?
Other than creating my own custom field editor is this the only way? Can the textDidChange(notification: NSNotification) not be interrogated to yield the keys pressed?
In using the control(_:textView:doCommandBySelector:) delegate method, how do I trap the pressing of keys that do NOT have standard key bindings. In particular, I want to intercept the key combination "shift+enter" which does not map to any standard selector. (Implied Question: can you only map to standard key-action methods in NSResponder?)
I believe I have achieved greater clarity with regard to the workings of NSTextField its delegates and its fieldEditor and its delegates. Yes, each one has its own delegate and the NSTextField is automatically set up as the delegate of the fieldEditor.
I was adding a delegate to the host NSTextField. This will NOT get called when the fieldEditor is firstResponder, which was what I was concerned with. This is also not the important delegate for the scenario above.
What appears to be useful is making the NSTextField conform to the NSTextViewDelegate protocol and specifically overriding the method:
func textView(textView: NSTextView, shouldChangeTextInRange affectedCharRange: NSRange, replacementString: String) -> Bool
to trap various keypresses.
The notification in textDidChange(notification: NSNotification) is not of use in this scenario because it is reported AFTER the keypress.
Intercepting pressed keys in textView:shouldChangeTextInRange:replacementString: is not ideal because that is called rather late, and is also called when the user pastes from the clipboard, for instance.
A probably cleaner way is to intercept textView:doCommandBySelector:, which gets called for all kinds of special keys such as tab, cursor, return and enter, for which you'll then get specific selectors that let you determine which special key was invoked.
For some keys, however, such as Return (CR) and Enter (ETX), you can't tell them apart, because both use the same "insertNewline:" selector.
In this case, you can check whether the currently handled event is a keydown event, and if so, check which key it was.
Here's a quick test code that lets you monitor the selector names and the involved keycode:
-(BOOL)textView:(NSTextView *)textView doCommandBySelector:(SEL)commandSelector
{
NSEvent *ev = self.view.window.currentEvent;
NSLog (#"selector: %s, key: %d", commandSelector, (int)ev.keyCode);
return NO;
}
I am making an app that will add sound to keypresses as the user types in an NSTextField. I need to capture keystrokes and know what each individual keypress is (like "d" or "space" or "6"). The app depends on this. There is no other way around it.
Each window is an NSDocument File Owner, and it has a single NSTextField in it, which is where the document data is parsed, and the user will type.
After hours of parsing the Internet for answers and hacking away at code, the four most commonly repeated answers are:
"that is not how things work, here is (irrelevant answer)"
"you are new to Cocoa, that is a bad idea, use control:textView:doCommandSelector:" that doesn't give me individual keys, and some keys need their own unique sound trigger.
"use controlTextDidChange: or textView:shouldChangeTextInRange:replaceString:" controlTextDidChange doesn't give me individual keys, and the second one only works for textViews or UIKit.
People get confused and answer with recommendations for UIKit instead of AppKit, which is iOS-only.
The weird thing is that if I subclass NSTextField, it receives -keyUp. I don't know where -keyDown is going.
So my ultimate question is: can you tell me some kind of step-by-step way to actually capture the keyDown that is sent to NSTextField? Even if it's a hack. Even if it's a terrible idea.
I would love to solve this problem! I am very grateful for your reading.
controlTextDidChange is quite a good solution, but don't forget this 2 important things:
Set the delegate binding of the textField to the object where you define the controlTextDidChange method. Commonly, in document based apps it is the window controller, otherwise your app delegate.
Set the textField's control to "continous" in the attribute inspector section
If you miss those points, you will have no result.
This is a pretty old question, but as I was trying to implement a NSTextField that could react to keyDown so that I could create a hotkey preferences control I found I wanted the answer to this question.
Unfortunately this is a pretty non-standard use and I didn't find any places that had a direct answer, but I've come up with something that works after digging through the documentation (albeit in Swift 4) and I wanted to post it here in case it helps someone else with a non-standard use case.
This is largely based off of the information gleaned from the Cocoa Text Architecture Guide
There are three components to my solution:
Creating your NSWindowController and setting a NSWindowDelegate on your NSWindow:
guard let windowController = storyboard.instanciateController(withIdentifier:NSStoryboard.SceneIdentifier("SomeSceneIdentifier")) as? NSWindowController else {
fatalError("Error creating window controller");
}
if let viewController = windowController.contentViewController as? MyViewController {
windowController.window?.delegate=viewController;
}
Your NSWindowDelegate
class MyViewController: NSViewController, NSWindowDelegate {
// The TextField you want to capture keyDown on
var hotKeyTextField:NSTextField!;
// Your custom TextView which will handle keyDown
var hotKeySelectionFieldEditor:HotKeySelectionTextView = HotKeySelectionTextView();
func windowWillReturnFieldEditor(_ sender: NSWindow, to client: Any?) -> Any? {
// If the client (NSTextField) requesting the field editor is the one you want to capture key events on, return the custom field editor. Otherwise, return nil and get the default field editor.
if let textField = client as? NSTextField, textField.identifier == hotKeyTextField.identifier {
return hotKeySelectionFieldEditor;
}
return nil;
}
}
Your custom TextView where you handle keyDown
class HotKeySelectionTextView: NSTextView {
public override func keyDown(with event: NSEvent) {
// Here you can capture the key presses and perhaps save state or communicate back to the ViewController with a delegate pattern if you prefer.
}
}
I fully admit that this feels like a workaround somewhat, but as I am experimenting with Swift at the moment and not quite up to speed with all of the best practices yet I can't make an authoritative claim as to the "Swift-i-ness" of this solution, only that it does allow a NSTextField to capture keyDown events indirectly while maintaining the rest of the NSTextField functionality.
Try like this if you print nslog you will get individual character record for example you pressd "A" you will get the same in console:-
-(void)controlTextDidChange:(NSNotification*)obj
{
NSLog(#"%#",[yourTextfield stringValue]);
}
Also, not sure this is only your requirement.
Text editing for an NSTextField is handled by an NSTextView provided by the window, called the field editor. See the NSWindow method fieldEditor:forObject: and the NSWindowDelegate method windowWillReturnFieldEditor:toObject:. I suppose you could use one of these to provide your own subclassed NSTextView as the field editor. Or, could you simply use NSTextView instead of NSTextField?
I subclassed NSWindows and implemented the keyDown: and keyUp: method like this:
- (void)keyDown:(NSEvent*)event
{
NSLog(#"Down: '%#'", [event characters]);
[super keyDown:event];
}
- (void)keyUp:(NSEvent*)event
{
NSLog(#"Up: '%#'", [event characters]);
[super keyUp:event];
}
If I pressed "W" key, it prints both my "Down" and "Up" correctly. But If I pressed Command+W combination, It prints ONLY the "Down" message, and windows' close action was not triggered. How should I do?
Command-W is typically the key equivalent of a menu item. It is handled by the menu when it is told to -performKeyEquivalent:. The menu item sends its action method to its target. The action method is typically -performClose: and the target is usually the first responder.
So, the normal processing of Command-W does not use the window's -keyDown: or -keyUp: at all.
If you want to control whether the window closes, have the window delegate implement -windowShouldClose:. If you want to be notified when the window is about to close, implement -windowWillClose: in the window delegate or observe the NSWindowWillCloseNotification notification.
Regarding keyboard handling, a quirk of -[NSApplication sendEvent:] is that it just doesn't dispatch any key up event if the Command key was down. If for some reason you really need to see the key up event, you'll have to implement a custom subclass of NSApplication, configure your Info.plist to make sure it's used, and implement an override of -sendEvent:.
I have a window with two NSButtons and an NSTextField along with several views and several other controls. I assign the right and left arrows keys to each of the two NSButtons. The two buttons respond to the right and left arrow keys. However, when in the NSTextField, I want the arrow keys to perform as the normally would in a text field and not trigger the NSButtons. I have tried reading through the Cocoa Key Handling documentation and other questions regarding key events, but I could not find an example of trying change the key equivalent behavior in one control. I tried subclassing the NSTextField but couldn't trap the arrow keys. How can this be implemented?
You can override becomeFirstResponder: and in your implementation call setKeyEquivalent:. If you want to remove the key equivalent when the button loses first responder status, override resignFirstResponder:.
Do this in the control whose first-responder status you want to affect the button's equivalent. For example, if you have a view as a container and it can become first responder, you'd override -becomeFirstResponder: (calling super) then manage the button's equivalent there. If you don't yet understand these topics, you have a lot of prerequisite reading to do because a simple answer isn't possible here.
You could subclass NSButton and override performKeyEquivalent: like so:
override func performKeyEquivalent(event: NSEvent) -> Bool {
guard
let window = window where window.firstResponder.isKindOfClass(NSText.self) == false
else {
return false
}
return super.performKeyEquivalent(event)
}
This essentially disables the key equivalent if the first responder is a text field/view.
I'm learning how to build programs with Cocoa. I'm using a sample Apple application that records video from a webcam. I'd like to start and stop the video by capturing the key press. I've tried to override the keydown event but I've read that it's not possible in an NSObject. How can I handle this kind of event?
The class of application extends a NSObject class.
This is the code:
- (void)keyDown:(NSEvent *)event {
NSLog(#"Hi there");
NSString *characters = [event characters];
if ([characters length]) {
switch ([characters characterAtIndex:0]) {
case NSUpArrowFunctionKey:
NSLog(#"Key UP");
break;
}
}
}
I've tried to override Keydown event but I've read that It's not possible in an NSObject.
Correct. Only a responder can respond to events.
How can I handle this kind of event?
Implement a responder. Subclassing NSWindow or NSWindowController will work. Make sure you make your actual window or window controller an instance of your subclass.
The Cocoa documentation explains further.
The class of application extends a NSObject class.
Why? Normally, the principal class of the application bundle is NSApplication or a subclass of that—and there aren't many good reasons to subclass NSApplication.
PS: What's a very good book to start learn MacOS Programming?
I didn't learn by the Hillegass book, myself (I stuck to Apple's docs), but it's a very popular recommendation and I have read it and can tell you it's good.
From the Cocoa Event-Handling Guide - The Responder Chain:
The responder chain is a linked series of responder objects to which an event or action message is applied. When a given responder object doesn’t handle a particular message, the object passes the message to its successor in the chain (that is, its next responder).
When you press a key the window receives the keyDown event. Then it dispatches the event to the first responder, that usually is the control with a blue bezel around its border (try to click on the address field in Safari or Firefox, when it's blue-bezeled then it has first-responder status).
If the first responder does not eat the keypress (the Safari address field does eat it when it displays a character) then it passes it down the responder chain to the next responder in the view hierarchy, then to the window and to the window controller as you can see in the Guide. (Take care that the action responder is another story.)
So you have to implement the keyDown: on a view of your window or in the window itself, if it has no views that eat events. The simplest way to test is to override the keyDown: method of an empty window
To put your hands into the inner workings you can even try overriding the sendEvent: method of a window. sendEvent: dispatches the events to the views of the window, and from there you can for example log all the events managed by the window.
Subclassing NSWindow or
NSWindowController will work.
Similarly, you can subclass NSView and override its event-handling methods.
What's a very good book to start learn
MacOS Programming?
Learn Objective-C on the Mac by Dalrymple is really straightforward, covers enough basics and moves fast enough to get you off the ground in a short bit. It touches on everything from Xcode and Interface Builder to OOP and Objective-C practices. Particularly helpful to beginners (IMHO) are the source file organization and Foundation kit chapters.
Best of luck!