NSTextView keyDown Event

Question

I want trigger the keyDown Event with every Key action. Therefore I have created a subclass of NSView.

@interface CodrTextView : NSView {
    NSTextField *lineNumberSpace;
    NSTextView *mainTextView;
}

- (id) initWithTextView:(NSTextView *)textView lineNumberSpace:(NSTextField *)textField;

I already have the method's:

- (id) initWithTextView:(NSTextView *)textView lineNumberSpace:(NSTextField *)textField {
   self = [self init];
   if (self){
       mainTextView = textView;
       lineNumberSpace = textField;
   }
   return self;
}

- (BOOL) acceptsFirstResponder {
   return YES;
}

- (BOOL)canBecomeKeyView {
   return  YES;
}

My plan is to count the lines in the textView and write the numbers in the lineNumberSpace. I know that the methods work, because I have test it already with an IBAction on a button. This is the method:

- (long) getLineCount{
    NSString *content = [mainTextView string];
    NSUInteger numberOfLines, index, contentLength = [content length];
    for (index = 0, numberOfLines = 0; index < contentLength; numberOfLines++){
         index = NSMaxRange([content lineRangeForRange:NSMakeRange(index, 0)]);
    }

    NSLayoutManager *layoutManager = [mainTextView layoutManager];
    NSUInteger numberOfGlyphs =[layoutManager numberOfGlyphs];
    NSRange lineRange;
    for (numberOfLines = 0, index = 0; index < numberOfGlyphs; numberOfLines++){
         (void) [layoutManager lineFragmentRectForGlyphAtIndex:index
                                           effectiveRange:&lineRange];
          index = NSMaxRange(lineRange);
    }
    numberOfLines++;
    return numberOfLines;
}

- (void)keyDown:(NSEvent *)event {
     NSMutableString *lineNumberString = [NSMutableString string];
     long numberOfLines = [self getLineCount];

     for (int i = 1; i <= numberOfLines; i++){
         [lineNumberString appendString:([NSString stringWithFormat:@"%d \n", i])];
     }
     [lineNumberSpace setStringValue:lineNumberString];
}

This method works surely. The problem is, with a button the number in the lineNumberSpace is changing correctly but with the keyDown Event it don't work. What is my mistake here?

Answer 1

Ahhh, looking at your code I now realize what the problem is.

Your "CodrTextView" object is not subclassed from "NSTextView" (and also, when you instantiate the object programatically or via your XIB or Storyboard, make sure the text view object is a custom class of "CodrTextView" and not just another "NSTextView"), so it's not actually getting the "acceptsFirstResponder" or "canBecomeKeyView" method calls either.

You need to descend "CodrTextView" from "NSTextView" instead of "NSView", OR you need to create another subclassed "NSTextView" object which will receive the "keyDown:" event and then it'll call the code that calculates the string that goes into "lineNumberSpace" of your main view.

Does this make sense to you now?