MyOpenGLView.m

#import "MyOpenGLView.h"

@implementation MyOpenGLView

- (id)initWithFrame: (NSRect)frameRect pixelFormat: (NSOpenGLPixelFormat*)format;
{
    self = [super initWithFrame:frameRect];
    if (self) {
        _pixelFormat = [format retain];

        [[NSNotificationCenter defaultCenter] addObserver: self
                                                 selector: @selector(_surfaceNeedsUpdate:)
                                                     name: NSViewGlobalFrameDidChangeNotification
                                                   object: self];
    }

    return self;
}

- (NSOpenGLContext*) openGLContext
{
    return _openGLContext;
}

- (void) _surfaceNeedsUpdate: (NSNotificationCenter*)notification
{
    [self update];
}

- (void) lockFocus
{
    NSOpenGLContext* context = [self openGLContext];

    [super lockFocus];
    if ([context view] != self)
    {
        [context setView: self];
    }
    [context makeCurrentContext];
}

- (void) drawRect
{
    NSOpenGLContext* context = [self openGLContext];

    [context makeCurrentContext];

    glClearColor(0, 0, 0, 0);
    glClear(GL_COLOR_BUFFER_BIT);
    glColor3f(1.0f, 0.85f, 0.35f);
    glBegin(GL_TRIANGLES);
    {
        glVertex3f(  0.0,  0.6, 0.0);
        glVertex3f( -0.2, -0.3, 0.0);
        glVertex3f(  0.2, -0.3 ,0.0);
    }
    glEnd();
    glFlush();

    [context flushBuffer];
}

- (void) viewDidMoveToWindow
{
    NSOpenGLContext* context = [self openGLContext];

    [super viewDidMoveToWindow];
    if ([self window] == nil)
        [context clearDrawable];
}

- (void) update
{
    [self drawRect];
}

- (NSOpenGLPixelFormat*) pixelFormat
{
    return _pixelFormat;
}

- (void)dealloc
{
    [super dealloc];
}

- (void)drawRect:(NSRect)dirtyRect
{
    // Drawing code here.
}

@end