android - http协议中的状态码不是可以反映所有的响应的情况，那为什么iOS 和安卓的还搞出-1001这种错误码出来？

Question

比方说
ios

-1000     NSURLErrorBadURL                    The connection failed due to a malformed URL.
-1001     NSURLErrorTimedOut                    The connection timed out.
-1002     NSURLErrorUnsupportedURL            The connection failed due to an unsupported URL scheme.
-1003     NSURLErrorCannotFindHost            The connection failed because the host could not be found.
-1004     NSURLErrorCannotConnectToHost        The connection failed because a connection cannot be made to the host.
-1005    NSURLErrorNetworkConnectionLost     The connection failed because the network connection was lost.
-1006     NSURLErrorDNSLookupFailed            The connection failed because the DNS lookup failed.
-1007     NSURLErrorHTTPTooManyRedirects        The HTTP connection failed due to too many redirects.
-1008    NSURLErrorResourceUnavailable           The connection’s resource is unavailable.
-1009     NSURLErrorNotConnectedToInternet"

为什么还要搞这些错误码出来？你是怎么看？

Answer 1

These are client side failures

If you cannot connect to the server, you will not be able to get the status returned by the server