making an iphone cube class - iphone

Question

I followed this tutorial and I'm currently trying to create a class to draw cubes. The class populates the buffers in a function called setup and draws them in a function called draw.
There are no errors however nothing is displayed on the screen.
My question is basicly how do I go about making a class from which I can render cubes.
Using Xcode 4.2, Opengl and Objective-C.
[edit]
-(void)SetShader:(GLuint)InShader
{
glUseProgram(InShader);
_positionSlot = glGetAttribLocation(InShader, "Position");
_colorSlot = glGetAttribLocation(InShader, "SourceColor");
glEnableVertexAttribArray(_positionSlot);
glEnableVertexAttribArray(_colorSlot);
_projectionUniform = glGetUniformLocation(InShader, "Projection");
_modelViewUniform = glGetUniformLocation(InShader, "Modelview");
_texCoordSlot = glGetAttribLocation(InShader, "TexCoordIn");
glEnableVertexAttribArray(_texCoordSlot);
_textureUniform = glGetUniformLocation(InShader, "Texture");
}
-(void)SetupVBO
{
GLuint vertexBuffer;
glGenBuffers(1, &vertexBuffer);
glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(CubeVertices), CubeVertices, GL_STATIC_DRAW);
GLuint indexBuffer;
glGenBuffers(1, &indexBuffer);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffer);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(CubeIndices), CubeIndices, GL_STATIC_DRAW);
}
-(void)draw
{
glVertexAttribPointer(_positionSlot, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), 0);
glVertexAttribPointer(_colorSlot, 4, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*) (sizeof(float) * 3));
glVertexAttribPointer(_texCoordSlot, 2, GL_FLOAT, GL_FALSE,
sizeof(Vertex), (GLvoid*) (sizeof(float) * 7));
glDrawElements(GL_TRIANGLES, sizeof(CubeIndices)/sizeof(CubeIndices[0]), GL_UNSIGNED_BYTE, 0);
}
-(void)render:(CADisplayLink*)displayLink
{
glClearColor(0, 0, 0.2, 1.0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glEnable(GL_DEPTH_TEST);
CC3GLMatrix *projection = [CC3GLMatrix matrix];
float h = 4.0f * self.frame.size.height / self.frame.size.width;
[projection populateFromFrustumLeft:-2 andRight:2 andBottom:-h/2 andTop:h/2 andNear:4 andFar:10];
glUniformMatrix4fv(_projectionUniform, 1, 0, projection.glMatrix);
CC3GLMatrix *modelView = [CC3GLMatrix matrix];
[modelView populateFromTranslation:CC3VectorMake(0, 0, -7)];
[modelView translateBy:CC3VectorMake(0,5,0)];
glUniformMatrix4fv(_modelViewUniform, 1, 0, modelView.glMatrix);
glViewport(0, 0, self.frame.size.width, self.frame.size.height);
[m_cube draw];
[_context presentRenderbuffer:GL_RENDERBUFFER];
}

Answer 1

It was as mentioned a problem with the arrangement of my viewport and perspective setups.