The template of OpenGL setup

setup.m

    
// Generate Vertex array object
glGenVertexArraysOES(1, &_triangleArray);
// Binding VAO
glBindVertexArrayOES(_triangleArray);
// Generate Vertex buffer object
glGenBuffers(1, &_triangleBuffer);
// Binding VBO
glBindBuffer(GL_ARRAY_BUFFER, _triangleBuffer);
// Send buffer data
glBufferData(GL_ARRAY_BUFFER, sizeof(gTriangleData), gTriangleData, GL_STATIC_DRAW);
   
glEnableVertexAttribArray(GLKVertexAttribPosition);
// glVertexAttribPointer(GLuint index, num of vertices, type of points, ?, num of bytes in one vertex, start pffset);
glVertexAttribPointer(GLKVertexAttribPosition, 3, GL_FLOAT, GL_FALSE, 24, BUFFER_OFFSET(0));
glEnableVertexAttribArray(GLKVertexAttribNormal);
glVertexAttribPointer(GLKVertexAttribNormal, 3, GL_FLOAT, GL_FALSE, 24, BUFFER_OFFSET(12));
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindVertexArrayOES(0);

update.m

/*
 * With GLKit, it is not necessary to reuse buffer object.
 * You only need to bind VAO.
 */
glBindVertexArrayOES(_triangleArray);
// Use compiled shader
glUseProgram(_program);
glUniformMatrix4fv(uniforms[UNIFORM_MODELVIEWPROJECTION_MATRIX], 1, 0, _modelViewProjectionMatrix.m);
glUniformMatrix3fv(uniforms[UNIFORM_NORMAL_MATRIX], 1, 0, _normalMatrix.m);
glDrawArrays(GL_TRIANGLES, 0, 3);