没有正确下载文件到 NSDocumentsDirectory？

Question

我想将文件下载到我的 NSDocumentsDirectory。我抓取一个作为下载链接的 url，并将该 url 存储到一个名为 url 的变量中这是我执行下载并将其存储到 Documents Directory 的代码，所以：

let data = NSURLConnection.sendSynchronousRequest(urlRequest, returningResponse: &response,error: &error)

if data != nil && error == nil{ 
  var documentsDirectoryUrl =  NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask).first as! NSURL
  documentsDirectoryUrl = documentsDirectoryUrl.URLByAppendingPathComponent(url.lastPathComponent)
  //Hold this file as an NSData and write it to the new location
  let fileData = NSData(contentsOfURL: NSURL(string:url)!)

  fileData!.writeToURL(documentsDirectoryUrl, atomically: false)   // true
  println("\(data!.length) bytes of data was written to Documents Directory.")
}
else if data!.length == 0 && error == nil{
  println("No data was returned")
}
else if error != nil{
  println("Error happened = \(error)");
}

由于我正在下载的文件是音乐文件，当我尝试从这些音乐文件播放音频时，当我尝试访问文件的路径时出现错误，因为该文件的路径设置为 nil。我认为这是下载文件的问题，因为我之前有代码工作，但后来我改变了下载音乐文件的方式，代码似乎中断了。任何帮助，将不胜感激。谢谢！

Answer 1

import UIKit


let documentsDirectoryUrl =  NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask).first as! NSURL

var error:NSError?
var response:NSURLResponse?

let data = NSURLConnection.sendSynchronousRequest(NSURLRequest(URL: NSURL(string: "http://i.stack.imgur.com/Xs4RX.jpg")!), returningResponse: &response, error: &error)

if let data = data where error == nil {
    let destinationUrl = documentsDirectoryUrl.URLByAppendingPathComponent(response!.suggestedFilename!)
    data.writeToURL(destinationUrl, atomically: true)   // true
    println("\(data.length) bytes of data was written to Documents Directory.")

}
if let error = error {
    println(error.description)
}