I have followed this guide.
Whereas I sincerely failed to understand what it says at point 13, I just have opened the pane of the inspector, but it doesn't say what attributes to set. However, I have copied and pasted the code in the proper classes. But it appears a normal window, without the triangle draw, just like when I make a normal program in Objective-C having an empty window.
Edit:
I thought that the problem was the initialization of the window, so I have written an awakeFromNib method to make the drawRect method start:
- (void) awakeFromNib
{
NSRect rect=NSMakeRect(100.0, 100.0, 100.0, 100.0);
[self drawRect: rect];
}
But at the first instruction of drawRect I get an EXC_BAD_ACCESS exception
glClearColor(0, 0, 0, 0);
Maybe the window is not initialized properly?