When does NSURLConnection's initWithRequest return nil
I believe this can also be used when it fails to load, not just initialize. (The alloc is done separately - that's where low mem would probably bite you) So (I'm guessing) it could fail because you did not have a network available (3G/Wifi) or it simply failed to connect to the server. In any event, use:
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
To get the actual failure.
You may be able to simulate this with an absence of a network - or even giving it a bad URL.
I guess the answer is "Never". Seems only way for NSURLConnection to return nil is failing at [super init]. ([super init] returning nil) But as super class of NSURLConnection is NSObject and NSObjects init just returns self (never nil)
PS: That's for IOS SDK 4.0, on emulator, can be different on device.
I would try all of the above except do it during low memory conditions. IE, I think it will happen when an internal malloc fails.