将JSON请求放在Dispatch_Async中是不好的做法？

Question

这是我用户登录时的Json请求。为了设置profileView，我需要更新UI，我在那里实例化下一个视图控制器。但是，在完全更新配置文件之前，我需要发出第二个JSON请求来获取图像。如果第一个JSON请求成功，我只能发出第二个JSON请求。在dispatch_async中创建另一个JSON请求是不好的做法吗？

jsonRequest.get(userCookie, url: userURL) { (succeedCookie: Bool, msg: String, results: Dictionary<String, Any>) -> () in

    var gotUserInfo = false
    if(succeedCookie) {
        println("It twerked! - you got the cookie", error: msg)
    }
    else {
        println(("It didn't twerk .. :( you no get cookie", error: msg))
    }
    // Move to the UI thread
    dispatch_async(dispatch_get_main_queue(), { () -> Void in
        if gotUserInfo {
            //
            // Second JSON request goes here
            //
            let vcTwo = self.storyboard?.instantiateViewControllerWithIdentifier("userProfile") as ProfileViewController
            //set future View variables here
            self.navigationController?.pushViewController(vcTwo, animated: true)
        }  
    })
}