Re: Keyboard Loop in Programmatically Created Window

FROM : Jerry Krinock
DATE : Tue Apr 03 17:17:34 2007

After re-reading Justin Bur's recent post on this topic [1], I 
resigned myself to the fact that there's probably some 
"implementation compromise" [2] which prevents the keyboard loop from 
working in a programatically-created window.  So, I bit the bullet 
and subclassed NSWindow to re-implement the keyboard loop in -
sendEvent: [3], and it looks like the problem is solved.

An interesting fact is that, in my re-implementation, if I ask for -
nextValidKeyView or -previousValidKeyView instead of -nextKeyView and 
-previousKeyView, it breaks again.  Nevertheless, at any time I can 
ask any of my buttons if they -acceptFirstResponder, and they smile 
and say YES.

So, my conclusion is that Cocoa somehow gets a bad first impression, 
or maybe no impression, of my programmatically-created subviews if 
they are not loaded from a nib.  After a bad impression, Cocoa 
forever thinks that they are not valid firstResponders.  Can anyone 
explain this more rigorously ???

Jerry Krinock


[1] http://www.cocoabuilder.com/archive/message/cocoa/2007/1/31/177975

[2] Non-Apple people may read this as "bug".

[3] Subclass of NSWindow to fix the problem...

@interface SSAlertWindow : NSWindow
@end

@implementation SSAlertWindow

- (void)sendEvent:(NSEvent *)event {
    int tab = 0 ;
    if ([event type] == NSKeyDown) {
        unichar character = [[event characters] characterAtIndex:0] ;
        if (character == 9) {
            tab = 1 ;
        }
        else if (character == 25) {
            tab = -1 ;
        }
    }

    if (!tab) {
        [super sendEvent:event] ;
    }
    else {
        NSView* firstResponder = (NSView*)[self firstResponder] ;
        NSView* nextResponder = (tab > 0)
            ? [firstResponder nextKeyView]
            : [firstResponder previousKeyView] ;
        [self makeFirstResponder:nextResponder] ;
    }
}

@end