How to detect if NSURLConnection's sendSynchronousRequest:returningResponse:error: ended up being timed out or other error

问题

I use NSURLConnection's sendSynchronousRequest:returningResponse:error: method (in a separate NSOperation thread) to connect to external server to retreive data. How do I know if the operation ended timed out, or some other network error?

回答1:

If there was an error, the error parameter will be non-nil when sendSynchronousRequest:returningResponse:error: returns.

You can retrieve the error code by checking the value returned by [NSError code]. The error code for time out is NSURLErrorTimedOut.

For instance:

NSError *error = nil;
[NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error]

if (error.code == NSURLErrorTimedOut) {
// Handle time out here
}

回答2:

Check this extension:

extension Error {

    var isConnectivityError: Bool {
        guard _domain == NSURLErrorDomain else { return false }

        let connectivityErrors = [NSURLErrorTimedOut,
                                  NSURLErrorNotConnectedToInternet,
                                  NSURLErrorNetworkConnectionLost,
                                  NSURLErrorCannotConnectToHost]

        return connectivityErrors.contains(_code)
    }
}

You can check in doc for other errors in NSURLError domain to expand your connectivityErrors array.

回答3:

You may present an alert to the user and pass the error parameter in sendSynchronousRequest:returningResponse:error: to the alert's message.

the code will be something like this:

[NSURLConnection sendSynchronousRequest: req returningResponse: &response error: &error];

if (error)
{
UIAlertView * alert = [[UIAlertView alloc]initWithTitle:@"Error" message:[error localizedDescription] delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
[alert show];
}

Hope it helps!!

来源：https://stackoverflow.com/questions/12818887/how-to-detect-if-nsurlconnections-sendsynchronousrequestreturningresponseerro

标签

objective-c

ios

cocoa

nsurlconnection