didReceiveResponse是否保證位於connectionDidFinishLoading之前？

Question

背景：在握手過程中，我的iOS應用學習通過

1. 服務器功能檢查它的頭信息didReceiveResponse

   和

2. 分析其響應XML中connectionDidFinishLoading

問題說明：由於回撥＃1在＃2之前，因此我將版本字符串存儲在didReceiveResponse中，並在響應可用時稍後在connectionDidFinishLoading中檢查它。

這個幸運的正常工作，到目前爲止，因爲＃1 preceeds 2＃。但是，這個訂單總是由網絡/ iOS保證的嗎？

Answer 1

根據文檔：

Zero or more connection:didReceiveResponse: messages will be sent to the delegate before receiving a connection:didReceiveData: message. The only case where connection:didReceiveResponse: is not sent to a delegate is when the protocol implementation encounters an error before a response could be created. Zero or more connection:didReceiveData: messages will be sent before any of the following messages are sent to the delegate: connection:willCacheResponse:, connectionDidFinishLoading:, connection:didFailWithError:.

所以，除非有一個錯誤，你能保證你會得到一個connectionDidFinishLoading之前得到didReceiveResponse。

Answer 2

是的，當然。在didReceiveResponse你可以檢查NSURLResponse，如果有什麼不對，你可以停止下載。因此connectionDidFinishLoading只會在您檢查回覆後纔會被調用。

Answer 3

從NSURLCOnnection Reference：

Zero or more connection:didReceiveResponse: messages will be sent 

to the delegate before receiving a connection:didReceiveData: message. The only case where connection:didReceiveResponse: is not sent to a delegate is when the protocol implementation encounters an error before a response could be created.

Zero or more connection:didReceiveData: messages will be sent 

before any of the following messages are sent to the delegate: connection:willCacheResponse:, connectionDidFinishLoading:, connection:didFailWithError:.

Zero or one connection:willCacheResponse: messages will be sent to 

the delegate after connection:didReceiveData: is sent but before a connectionDidFinishLoading: message is sent.

所以，它不僅會如果創建響應之前的錯誤發生。