如果您希望 MakeGetRequest 方法返回通过 dataTaskWithURL 你不能。该方法执行异步调用，这很可能在 MakeGetRequest 已经返回后完成 - 但是更一般地，它不能以确定性的方式知道。

If you want the MakeGetRequest method to return data obtained via dataTaskWithURL, you can't. That method performs an asynchronous call, which is most likely completed after the MakeGetRequest has already returned - but more generally it cannot be know in a deterministic way.

通常，异步操作通过闭包处理 - 而不是返回数据的方法，你向它传递一个闭包，接受在你的代码版本中返回的参数 - 完成 dataTaskWithURL ，您调用完成处理程序关闭，提供适当的参数：

Usually asynchronous operations are handled via closures - rather than your method returning the data, you pass a closure to it, accepting the parameters which are returned in your version of the code - from the closure invoked at completion of dataTaskWithURL, you call that completion handler closure, providing the proper parameters:

class func MakeGetRequest(urlString: String, completionHandler: (data: NSData, error: NSError) -> Void) -> Void
{
    let url = NSURL(string: urlString)
    var dataResponse: NSData
    var err: NSError

    let task = NSURLSession.sharedSession().dataTaskWithURL(url!, completionHandler: { (data, response, error) -> Void in
        completionHandler(data: data, error: error)
    })

    task.resume()
}