glCompileShader

+ (BOOL)compileShader:(GLuint *)shader type:(GLenum)type file:(NSString *)file
{
    GLint status;
    const GLchar *source;

    source = [[NSString stringWithContentsOfFile:file
                                        encoding:NSUTF8StringEncoding
                                           error:nil] UTF8String];
    if (!source) {
        NSLog(@"Failed to load shader (%s)", [file UTF8String]);
        return NO;
    }

    *shader = glCreateShader(type);
    glShaderSource(*shader, 1, &source, NULL);
    glCompileShader(*shader);

#if defined(DEBUG)
    GLint logLength;
    glGetShaderiv(*shader, GL_INFO_LOG_LENGTH, &logLength);
    if (logLength > 0) {
        GLchar *log = (GLchar *)malloc(logLength);
        glGetShaderInfoLog(*shader, logLength, &logLength, log);
        NSLog(@"Shader compile log:\n%s", log);
        free(log);
    }
#endif

    glGetShaderiv(*shader, GL_COMPILE_STATUS, &status);
    if (status == 0) {
        glDeleteShader(*shader);
        return NO;
    }

    return YES;
}