Question

I have 3 subclasses: a Block class, a Row class and a Table class. All are subclasses of NSView.
I have a Table added with IB which programmatically displays 8 rows, each of which displays 8 blocks. I overrode the mouseDown: method in Block to change the background color to red, but it doesn’t work. Still if I add a block directly on top of the Table with IB it does work so I can’t understand why it won’t work in the first case.

Here’s the implementation code for Block and Row (Table’s implementation works the same way as Row’s):

//block.m

- (void)drawRect:(NSRect)dirtyRect
{
    [color set];
    [NSBezierPath fillRect:dirtyRect];
}

-(void)mouseDown:(NSEvent *)theEvent
{
    color = [NSColor redColor];
    checked = YES;
    [self setNeedsDisplay:YES];
}

//row.m

- (void)drawRect:(NSRect)dirtyRect
{

    [[NSColor blueColor] set];
    [NSBezierPath fillRect:dirtyRect];
    int x;
    for(x=0; x<8; x++){
    int margin = x*2;
    NSRect rect = NSMakeRect(0, 50*x+margin, 50, 50);
    Block *block = [[Block alloc] initWithFrame:rect];
    [self addSubview:block];
    }
}

Answer 1

I understood the problem… since the mouseDown implementation would cause the block to redraw, and so even its superview, it would call Table’s drawRect: method causing it to draw new blocks on top of the old ones, and so it would seem never to change color. So I created a property for Table called isFirstAppearance initially set to YES which if YES makes the table draw the rows and sets itself to NO.