NSURLSession 3xx重定向和完成处理程序

问题描述

我有一个dataTask + completeHandler方法，用于从Web服务器下载数据.到目前为止，我已经实现了:

I have a dataTask + completionHandler approach to downloading data from a web server. So far I have implemented this:

let task = session.dataTaskWithURL(url, completionHandler: {
        (pageData,response,error) in
...
...
let code = urlHttpResponse.statusCode
switch code {
case 200:
     self.fetchedPages.updateValue(pageData, forKey: pageNumber)
case 404:
    self.fetchedPages.updateValue(nil, forKey: pageNumber) //No data exists for that page
default:
    self.fetchedPages.updateValue(nil, forKey: pageNumber) //No gurantee data exists for that page
}
NSNotificationCenter.defaultCenter().postNotificationName("pageDataDownloaded", object: self, userInfo: ["numberForDownloadedPage":pageNumber])

我想知道，如果statusCode是3xx错误，会发生什么?pageData会在重定向位置包含数据吗?换句话说，我应该添加

What I'm wondering is what happens if statusCode is a 3xx error? Will pageData contain the data at the redirected location? In other words, should I add

case _ where code >= 300 && code < 400:
    self.fetchedPages.updateValue(pageData, forKey: pageNumber)

还是会使用包含重定向位置的值和新的200状态代码的pageData再次调用处理程序?还是在正确处理重定向时，我只能使用委托来做某事?

Or will the handler get called again with pageData containing the value at the redirected location and a fresh 200 status code? Or is handling redirects properly something I can only do using a delegate?

推荐答案

如果您没有委托，或者委托没有实现 URLSession(_:task:willPerformHTTPRedirection:newRequest:completionHandler:) ，将自动遵循HTTP重定向.在这种情况下，您不会在处理程序中看到30倍的状态.

If you don't have a delegate or the delegate doesn't implement URLSession(_:task:willPerformHTTPRedirection:newRequest:completionHandler:), HTTP redirects will be automatically followed. In that case, you won't see the 30x statuses in your handler.

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