Visible bounds of text in Cocoa

- (void)drawRect:(NSRect)dirtyRect
{
    NSFont *font = [NSFont fontWithName:@"Zapfino" size:40.0];
    NSAttributedString *string = [[NSAttributedString alloc] initWithString:@"flapfino\ntest" attributes:[NSDictionary dictionaryWithObject:font forKey:NSFontAttributeName]];

    NSTextStorage *textStorage = [[NSTextStorage alloc] initWithAttributedString:string];
    NSLayoutManager *layoutManager = [[NSLayoutManager alloc] init];
    NSTextContainer *textContainer = [[NSTextContainer alloc] initWithContainerSize:NSMakeSize(FLT_MAX, FLT_MAX)];
    [layoutManager addTextContainer:textContainer];
    [textStorage addLayoutManager:layoutManager];

    NSUInteger numGlyphs = [layoutManager numberOfGlyphs];
    NSRange glyphRange = NSMakeRange(0, numGlyphs);

    NSRect visibleBounds = NSZeroRect;
    for (NSUInteger i = glyphRange.location; i < glyphRange.location + glyphRange.length; ++i) {
        NSPoint offsetForGlyph = [layoutManager locationForGlyphAtIndex:i];
        offsetForGlyph.y += NSMinY([layoutManager lineFragmentRectForGlyphAtIndex:i effectiveRange:NULL]);
        NSRect boundingRectForGlyph = [[textStorage font] boundingRectForGlyph:[layoutManager glyphAtIndex:i]];
        if ([self isFlipped])
            boundingRectForGlyph.origin.y = - NSMinY(boundingRectForGlyph) - NSHeight(boundingRectForGlyph);
        visibleBounds = NSUnionRect(visibleBounds, NSOffsetRect(boundingRectForGlyph, offsetForGlyph.x, offsetForGlyph.y));
    }

    NSRect viewBounds = [self bounds];
    NSPoint offsetForCentering = NSMakePoint(NSWidth(viewBounds) / 2 - NSWidth(visibleBounds) / 2 - NSMinX(visibleBounds), NSHeight(viewBounds) / 2 - NSHeight(visibleBounds) / 2 - NSMinY(visibleBounds));

    [layoutManager drawGlyphsForGlyphRange:glyphRange atPoint:offsetForCentering];

    NSRect typographicBounds = [layoutManager usedRectForTextContainer:textContainer];
    [[NSBezierPath bezierPathWithRect:NSOffsetRect(typographicBounds, offsetForCentering.x, offsetForCentering.y)] stroke];

    [[NSBezierPath bezierPathWithRect:NSOffsetRect(visibleBounds, offsetForCentering.x, offsetForCentering.y)] stroke];
}

- (BOOL)isFlipped
{
    return YES;
}