Re: NSURLConnection canHandleRequest: succeeds even with no network

FROM : Jens Alfke
DATE : Sat May 24 23:25:54 2008

On 23 May '08, at 11:11 PM, Mike wrote:

> Why does [ NSURLConnection canHandleRequest: ] return YES even if I 
> turn off all my network connections? I thought this method was 
> supposed to be used for preflighting connection requests?


No, it just tells you whether there's support for that URL scheme 
(http:, ftp:, etc.)

If you want to tell whether the host is reachable, you need to use the 
System Configuration API — look up the docs for 
SCNetworkCheckReachabilityByName. (I also just noticed 
CFHostGetReachability, which looks like a higher-level interface that 
might be easier to call.)

Even this just checks the system's network interfaces and routing 
tables to decide whether the kernel knows how to route a packet 
towards that address — it does _not_ actually try to contact the 
server, so it can't tell you if there's a broken gateway, or the 
server is down, or it's not listening on the port you want to connect 
to, etc.

—Jens