Check for OpenGL ES extensions

GC_OES_Ext_Check.h

// as recommended by Apple

BOOL CheckForExtension(NSString *searchName)
{
    NSString *extensionsString = [NSString stringWithCString:glGetString(GL_EXTENSIONS) encoding:NSASCIIStringEncoding];
    NSArray *extensionsNames = [extensionsString componentsSeparatedByString:@" "];
    return [extensionsNames containsObject:searchName];
}

// e.g. check for PowerVR Texture Compression format

if (CheckForExtension(@"GL_IMG_texture_compression_pvrtc"))
{
    // continue...
}