Problem with adding many tool tips to a view

My Cocoa application has a view with about fifty colored rectangles to be displayed, which开发者_运维技巧 represents a heat map of some data. I cannot figure out how to add tool tips to each of the rectangles showing information about the data which that rectangle represents. I looked at the developer documentation for NSView and have added the following code:

- (NSString *)view:(NSView *)view stringForToolTip:(NSToolTipTag)tag point:(NSPoint)point userData:(void *)data
{

    // use the tags to determine which rectangle is under the mouse
    if (tag == blueTag) {
        return NSLocalizedString(@"The Blue rectangle", @"");
    }
    if (tag == redTag) {
        return NSLocalizedString(@"The Blue rectangle", @"");    
    }
    // we should never get to here!
    return NSLocalizedString(@"Unknown tooltip area", @"");
}

// add tooltips for the rectangles (in my  drawRect method 
// after the rects have been initialized etc.)
[self removeAllToolTips];
redTag = [self addToolTipRect:startingRect owner:self userData:NULL];
blueTag = [self addToolTipRect:blueRect owner:self userData:NULL];

I run into two issues:

1) when I print out the tag for the tooltips, they both show 1 as the tag even though they are for two different rectangles.

2) the stringForToolTip method is never called

Any help/suggestions would be great. Thanks!

I think the main problem is that you're adding the tool tip rects in -drawRect:. You only need to update the tooltip rects if the view is resized, not every time it's drawn. Instead, add a method to configure the tooltip rects and then call that from your view's -init method.

You can then override -setFrame: and call your tooltip configuration method after calling [super setFrame:newFrame].

I should point out that in your code both rectangles will output The Blue rectangle because the log strings are the same...