Swift 打印响应正文而不是标题

我当前的代码打印标题信息，但我需要正文响应。我正在尝试获取用于另一个请求的令牌

    request.httpMethod = "GET"
    request.allHTTPHeaderFields = headers

    let session = URLSession.shared
    let dataTask = session.dataTask(with: request as URLRequest, completionHandler: { (data, response, error) -> Void in
        if (error != nil) {
            print(error!)
        } else {
            let httpResponse = response as? HTTPURLResponse
            print(httpResponse!)
        }})
    dataTask.resume()

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响应的内容位于

dataTask（with:request）

的completion块的

data

变量中