Swift：HTTP请求正确执行，但HTTPS无法正常工作

Question

我尝试通过此代码通过HTTP执行GET请求：

func httpGet(request: NSURL, callback: (String, String) -> Void) {
    let session = NSURLSession.sharedSession()
    let task = session.dataTaskWithURL(request) {
        (data,response,error) -> Void in
        if (error != nil) {
            callback("", error!.localizedDescription)
        } else {
            let result = NSString(data: data!, encoding: NSASCIIStringEncoding)
            callback(result! as String, "")
        }
    }
    task.resume()
}

func updateIssueList () {
    httpGet(NSURL(string: "http://www.google.com")!) {
        (data, error) -> Void in

        print("error: \(error)")
        print("data: \(data)")
    }
}

它已正确执行，并且无错误地返回数据。但是当我将协议更改为HTTPS（https://www.google.com“）时，请求失败。当我尝试在设备上运行应用程序（iPhone 4s）时，我收到了

Error Domain=NSURLErrorDomain Code=-1005 "The network connection was lost." UserInfo=0x17579730 {NSErrorFailingURLStringKey=https://www.google.com, NSErrorFailingURLKey=https://www.google.com, NSLocalizedDescription=The network connection was lost., NSUnderlyingError=0x1758e470 "The network connection was lost."}

在模拟器上，两种变体都能正常工作。我做错了什么？