Get keyDown event for an NSTextField

Question

In xcode last version, I am trying to get the keyDown event of an NSTextField. However, despite following multiple tutorials on the internet (delegates, controllers...), I still can't receive it.

Any easy hint for me ?

Thanks !

Due to how field editors work, it's a bit complex. What are you actually trying to do? — 一二三, Jan 15 '12 at 09:05

score 14 · Answer 1 · edited Mar 13 '14 at 22:37

I got sick of all the non answers to do it some other way people so I put my nose down and figured out a way to make this work. This isn't using keydown event directly but it is using the keydown in the block. And the behavior is exactly what I wanted.

Subclass the text field

.h

@interface LQRestrictedInputTextField : NSTextField

.m

In the become first responder setup a local event

static id eventMonitor = nil;

- (BOOL)becomeFirstResponder {
    BOOL okToChange = [super becomeFirstResponder];
    if (okToChange) {
        [self setKeyboardFocusRingNeedsDisplayInRect: [self bounds]];

        if (!eventMonitor) {
            eventMonitor = [NSEvent addLocalMonitorForEventsMatchingMask:NSKeyDownMask handler:^(NSEvent *event) {

                NSString *characters = [event characters];
                unichar character = [characters characterAtIndex:0];
                NSString *characterString=[NSString stringWithFormat:@"%c",character];

                NSArray *validNonAlphaNumericArray = @[@" ",@"(",@")",@"[",@"]",@":",@";",@"\'",@"\"",@".",@"<",@">",@",",@"{",@"}",@"|",@"=",@"+",@"-",@"_",@"?",@"#",
                                                   @(NSDownArrowFunctionKey),@(NSUpArrowFunctionKey),@(NSLeftArrowFunctionKey),@(NSRightArrowFunctionKey)];

                if([[NSCharacterSet alphanumericCharacterSet] characterIsMember:character] || character == NSCarriageReturnCharacter || character == NSTabCharacter || character == NSDeleteCharacter || [validNonAlphaNumericArray containsObject:characterString ] ) { //[NSCharacterSet alphanumericCharacterSet]
                }  else {
                    NSBeep();
                    event=nil;
                }
                return event;
            } ];

        }
    }
    NSLog(@"become first responder");
    return okToChange;
}

remove the event once the textfield editing ends

Also if you're using ARC I noticed you might need to assign the textview string to the stringValue. I nslog'd the stringValue and the value was retained. Without the nslog I had to assign the notification object string to the stringValue to keep it from getting released.

-(void) textDidEndEditing:(NSNotification *)notification {
    [NSEvent removeMonitor:eventMonitor];
    eventMonitor = nil;

    NSTextView *textView=[notification object];
    self.stringValue=textView.string;
}

it works like a charm. I just put the remove event call in the resignFirstResponder method to mirror the adding placement — Jim75, Mar 19 '19 at 08:51

score 5 · Answer 2 · answered Jan 15 '12 at 10:01

5

You can subclass NStextField and use keyUp that works for NSTextField.

in .h

@interface MyTextField : NSTextField <NSTextFieldDelegate>

in .m

-(void)keyUp:(NSEvent *)theEvent {
    NSLog(@"Pressed key in NStextField!");
}

answered Jan 15 '12 at 10:01

Justin Boo

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1

You can just use the delegate method instead of sub-classing. You also need to set the NSTextField's delegate to File's Owner. That's the most simple way, at least. – Kieran Senior Feb 14 '13 at 17:43
This doesn't answer the question, which asks for keyDown – j b Mar 22 '14 at 20:26
Jamie, KeyDown is another delegate function. – Sebastian Apr 11 '16 at 11:31

score -3 · Answer 3 · answered Jan 15 '12 at 09:17

Add UITextFieldDelegate to your .h like this

@interface ViewController :  UIViewController <UITextFieldDelegate> {

Then you can use this to detect every key press in a text field

-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string

Return YES to allow the character that was pressed to be inserted into the field but you can add whatever code you need in here.

Get keyDown event for an NSTextField

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