Question

I have a regular DocumentView class in a Window. I have the following code once a user presses a button:

- (void)handleButtonPress:(NSNotification *)note{
  // draw new graph view
  EDGraphView *graph = [[EDGraphView alloc] init];
  [self addSubview:graph];
  [self setNeedsDisplay:TRUE];

  NSLog(@"Button was pressed");
}

This gets called correctly because I get the output “Button was pressed” every time I click on the button. In addition to that the drawRect method below of the view gets called as well.

- (void)drawRect:(NSRect)dirtyRect
{
  NSRect bounds = [self bounds];
  [[NSColor whiteColor] set];
  [NSBezierPath fillRect:bounds];

  for(EDGraphView *graph in [self subviews]){
    [graph setNeedsDisplay:TRUE];
    NSLog("calling set needs display on graph object!");
  }
}

However when I go in the EDGraphView class and edit the drawRect method to look like the following

- (void)drawRect:(NSRect)dirtyRect
{
  NSLog(@"redrawing graph view.");
}

It never gets called! I must be missing something about the whole setNeedsDisplay and drawRect process.

Any suggestions?

Answer 1

Got it…I needed to make the following init call on my subview:

EDGraphView *graph = [[EDGraphView alloc] initWithFrame:bounds];

Now it calls the drawRect method!