In my MAC app, in one use case, I prompt an window to the user and give him 2 options (say buttons Save and Cancel). I want to force the user to select either of the 2 buttons to close the window.
But currently I find that if the user hits "Command + w" key when window has the focus, the window gets closed. In the .xib resource file, I uncheck the "close" option but that only disables the close option in the window UI.
How do I make sure that my window ignores the "Command+w" key and stays as is without closing.
Have also tried removing the notification by adding below code in awakeFromNib method but did not help.
[[NSNotificationCenter defaultCenter] removeObserver:NSWindowWillCloseNotification ];
Have also tried to implement "windowShouldClose" delegate method and return NO, but this method is never called. The documentation too says that this method is not reliable.
You should use an NSAlert for this sort of prompt, probably run as a sheet on the window. That would avoid the problem of closing it.
In any case, the window's delegate can implement -windowShouldClose: to control if a window is allowed to close. You can make an object (often the window controller) be its delegate by declaring that it adopts the NSWindowDelegate protocol and connecting the window's delegate outlet to that object.
I recently had to solve a similar problem. I'm not sure that this is the 'right' way to do it. But it worked for my purposes, and might work for you.
By default, I think, the 'Close Window' (CMD+W) menu item is bound to the action 'performClose' on first-responder. If you remove this binding and instead bind to a custom IBAction on your application delegate or main window controller, it allows you to conditionally call the close method of the current key-window if it is not matching the instance that you want to keep alive.
#property (strong, nonatomic) MyWindowController *unstoppable;
-(IBAction)killActiveWindow:(id)sender
{
NSWindow *keyWindow = [[NSApplication sharedApplication]keyWindow];
if ([keyWindow isNotEqualTo: unstoppable.window]){
NSLog(#" CMD+W Closing Window %#",keyWindow.title);
[keyWindow close];
}
}
Normally closing a window with option key down closes all the windows in the application. In my application, I'd like it to close only windows related to the window that the user was closing. How can I do that? I can implement windowShouldClose for all my windows, but how can I know which window the user clicked on?
You can see if the option key was held down in the event that is being processed like this:
([[NSApp currentEvent] modifierFlags] & NSAlternateKeyMask)!=0
If this is in response to the user clicking the window's close button, then you can find the window that was clicked like this: [[NSApp currentEvent] window]
I suppose you should also check that [NSApp currentEvent] is a mouse event, etc., but it seems like this combination of tests should get you the info that you want.
If, on the other hand, this is the user choosing the "Close Window" command from the "File" menu with the option key held down, you can override the performClose: method from NSWindows default implementation to your own, where you would do the currentEvent test above before calling [super performClose: sender]
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)
}
I have an NSMenu that contains NSMenuItems with custom views. I want it so that when the alt button is pressed, the menu items would change part of their look (through their view). I found setAlternative in the NSMenuItem docs, however, in practice I could only get it to work with NSMenuItems without custom views. As soon as I set a custom view, all of the menu items would be displayed.
Also, I tried getting keypress events while the menu was open. Due to the other run loop, NSApplication's sendEvent: doesn't receive events until after the menu is closed. Therefore, I can't just intercept the event coming in.
Does anyone know how I can get notified, whether through delegation or subclassing, of when the alt key is pressed when a menu is opened?
You should set an object as the delegate of your menu and then implement the delegate method -menu:updateItem:atIndex:shouldCancel:.
This will allow you to change the state of your custom view before the menu item is displayed, based on the current modifier state.
You can get the current modifiers by asking for [[NSApp currentEvent] modifierFlags].
If you need to be notified if the modifier flags change while your menu is open, implement the -flagsChanged: method in your custom view:
- (void)flagsChanged:(NSEvent*)event
{
if ([event modifierFlags] & NSAlternateKeyMask) // check for option key
{
//do something
}
else
{
//do something else
}
}
Below is the sample code.
- (void) keyDown: (NSEvent *) event
{
NSString *chars = [event characters];
unichar character = [chars characterAtIndex: 0];
if (character == 27) {
NSLog (#"ESCAPE!");
}
}
Should I need to set any delegate in InterfaceBuilder or any kinda binding??
Help Appreciated...
keyDown needs to be overridden in an NSView subclass whose object is set as first responder. The responder chain should pass down the event, but to be sure you get it, make sure that your object is first responder.
In cocoa only views participate in responder chain for this event. So you should override a some view method. The easy way is to find out what view is first responder for particular event you want to handle and use it.
window sends keyDown(with: ) stright to first responder which could handle it or pass up to responder chain. Not all views pass the events up. NSCollectionView doesn't pass the key event. It plays a bump sound instead.
It is also possible that a key you want to handle is a Key equivalent read more here. If so you should override performKeyEquivalent(with: ) method to receive this type of events instead. This events unlike keyDown events passed down from the window to the all subviews until someone handle them.
As mentioned NSCollectionView keyDown(with: ) method do not pass the key events up the responder chain. To handle such events in one of it's super views you should override it in collection view first and send event manually by calling self.nextResponder?.keyDown(with: event) for such events that you want to handle by yourself.