Quick detecting, if server is offline

Question

We use a PHP server and an iOS app.

I use NSURLConnection to send a message to the server. If server is unavailable, e.g. the address is incorrect then we wait for an error after 60–90 secs. This is a long time.

How do I decrease this time? Is there any quick function to check for server availability?

If I first call

[request setTimeoutInterval:10];
[request setHTTPBody:[message data]];

when I check [request timeoutInterval] it is still 240, not 10. So interesting..

If I add a setTimeoutInterval: call before the connection is created like so:

[request setTimeoutInterval:10];
connection = [[NSURLConnection alloc] initWithRequest: request delegate: self];

The request still returns after a long time.

Answer 1

Yeah, timeouts don't quite work like you would expect. One solution is to set up a timer that cancels the connection after your desired interval has elapsed. I did this in my ReallyRandom class, and it seems to do the trick.

It looks something like this:

connection = [[NSURLConnection alloc] initWithRequest: request delegate: self startImmediately:NO];

timer = [NSTimer scheduledTimerWithTimeInterval:10
                                     target:self
                                   selector:@selector(onTimeExpired)
                                   userInfo:nil
                                    repeats:NO];

[connection start];


// When time expires, cancel the connection
-(void)onTimeExpired
{
    [self.connection cancel];
}