OpenGL texture not showing up (with cocoa) - objective-c

Question

It's a very strange problem. I create a texture using the method copied from apple's sample. It's works fine in apple's sample, but not in mine project. The texture is not shows up, only the color define by glcolor4f. I used glistexture and glgeterror to check, they tells that nothing wrong there. This only happens at the first time I load the texture. If I release the texture and reload it, It works, with the same code. Are there any other ways to check errors of OpenGL?
here's the code I'm using to load the texture:
- (FETexture *)loadTextureWithPath:(NSString*)name{
NSURL *url = nil;
CGImageSourceRef src;
CGImageRef image;
CGContextRef context = nil;
CGColorSpaceRef colorSpace;
GLuint textureId;
GLuint pboId;
GLubyte *data;
url = [NSURL fileURLWithPath: name];
src = CGImageSourceCreateWithURL((__bridge CFURLRef)url, NULL);
if (!src) {
NSLog(#"No image");
return nil;
}
image = CGImageSourceCreateImageAtIndex(src, 0, NULL);
CFRelease(src);
GLuint width = (GLint)CGImageGetWidth(image);
GLuint height = (GLint)CGImageGetHeight(image);
data = (GLubyte*) calloc(width * height * 4, sizeof(GLubyte));
colorSpace = CGColorSpaceCreateDeviceRGB();
context = CGBitmapContextCreate(data, width, height, 8, 4 * width, colorSpace, kCGImageAlphaPremultipliedFirst | kCGBitmapByteOrder32Host);
CGColorSpaceRelease(colorSpace);
// Core Graphics referential is upside-down compared to OpenGL referential
// Flip the Core Graphics context here
// An alternative is to use flipped OpenGL texture coordinates when drawing textures
CGContextTranslateCTM(context, 0.0, height);
CGContextScaleCTM(context, 1.0, -1.0);
// Set the blend mode to copy before drawing since the previous contents of memory aren't used. This avoids unnecessary blending.
CGContextSetBlendMode(context, kCGBlendModeCopy);
CGContextDrawImage(context, CGRectMake(0, 0, width, height), image);
CGContextRelease(context);
CGImageRelease(image);
glGenTextures(1, &textureId);
glGenBuffers(1, &pboId);
// Bind the texture
glBindTexture(GL_TEXTURE_2D, textureId);
// Bind the PBO
glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pboId);
// Upload the texture data to the PBO
glBufferData(GL_PIXEL_UNPACK_BUFFER, width * height * 4 * sizeof(GLubyte), data, GL_STATIC_DRAW);
// Setup texture parameters
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
// OpenGL likes the GL_BGRA + GL_UNSIGNED_INT_8_8_8_8_REV combination
// Use offset instead of pointer to indictate that we want to use data copied from a PBO
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0,
GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, 0);
// We can delete the application copy of the texture data now
free(data);
glBindTexture(GL_TEXTURE_2D, 0);
glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
FETexture *texture = [FETexture new];
texture.textureID = textureId;
texture.bufferID = pboId;
texture.width = width;
texture.height = height;
return texture;

Answer 1

You've not shown any of the relevant code for the draw site. Perhaps you're not binding this texture at draw time.
You can use the OpenGL Profiler in "Graphics tools for Xcode" at https://developer.apple.com/downloads/index.action to debug GL errors and state.