Youtube登录验证失败

Question

当我进行youtube登录验证时，代码如下：

'GTMOAuth2ViewControllerTouch * viewController;     viewController = [[GTMOAuth2ViewControllerTouch alloc] initWithScope：scope                                                                 clientID的：kMyClientID                                                             clientSecret：kMyClientSecret                                                         keychainItemName：kKeychainItemName                                                                 委托：自我                                                         finishedSelector：@selector（的viewController：finishedWithAuth：错误：）];

[self presentViewController:viewController animated:YES completion:nil];'

运行后身份验证失败。但是当认证成功时我将clientSecret设置为nil，为什么？