无法删除 swift 中 NSURLConnection 中的 NSData 值

Unable to delete NSData values in NSURLConnection in swift

我正在 UITableView 中填充约会列表。单击 viewappointment 按钮后,约会值将通过 API 并使用 NSURLConnection 获取值。成功获得 5 个约会并填充到 UITableView 中。

如果我再次单击该按钮,将显示 10 个约会。 如果我再次单击,将显示 15 个约会。

重复相同的数据。我不知道如何停止重复。

我已经使用下面的行删除了在追加新数据之前已经存在的所有数据。请指导我。

appoApiData.setData(NSData())  //TO REMOVE ALL DATAS

编码部分:

//BUTON ACTION: 
appointmentAPI() //FUNCTION CALL

    func appointmentAPI()
    {
        let url = NSURL(string: baseURL + "appointment/getbyuser/" + String(sharedResources.shared.id))
        let request = NSMutableURLRequest(URL: url!)

        appoApiConnection = NSURLConnection(request: request, delegate: self)! //NSURLConnection Delegates Method Call

        println("URL CONNEXN \(appoApiConnection)")
    }

    //NSURL CONNECTION DELEGATES  
    func connection(connection: NSURLConnection!, didReceiveResponse response: NSURLResponse!)
    {
        if(connection == appoApiConnection)
        {
            println("RESPONSE_APPO: \(response)")
        }

    }

    func connection(connection: NSURLConnection!, didReceiveData conData: NSData!)
    {
        if(connection == appoApiConnection)
        {
            appoApiData.setData(NSData()) //CLEARING ALL PREVIOUS VALUES
            self.appoApiData.appendData(conData)
            println("appo_data  \(appoApiData.length)")

            //Button Click 1st time: appo_data = 5 
            //Button Click 1st time: appo_data = 10 
            //Button Click 1st time: appo_data = 15
            // and so on.... 
        }
    }

didReceiveResponse 中将 NSMutableData 实例的长度设置为 0

func connection(connection: NSURLConnection!, didReceiveResponse response: NSURLResponse!)
{
    if(connection == appoApiConnection)
    {
      appoApiData.length = 0            
      println("RESPONSE_APPO: \(response)")
    }
}

并删除 appoApiData.setData(NSData())