iOS5 NSURLConnection methods deprecated

Question

I'm trying to write an iOS app that makes asynchronous requests to get data over the network. It seems like a lot of people recommend using NSURLConnection for this, and frequently mention the delegate method connection:didReceiveData:.

Unfortunately, I cannot for the life of me find out where this delegate method is documented. For one, it is not in the protocol reference for NSURLConnectionDelegate. It is listed in the NSURLConnection Class Reference, but has apparently been deprecated as of iOS5. The documentation does not explain why it was deprecated, or what developers should use instead to achieve similar functionality.

What am I missing? A lot of what I've read seems to imply that big changes were made to NSURLConnection for iOS5. Where are these changes documented? Is the documentation of delegate methods complete?

Thanks

Answer 1

Fishing around the header files tells me that the methods were moved from an informal protocol (which is a deprecated Obj-C pattern) into a formal delegate protocol called NSURLConnectionDataDelegate that's in NSURLConnection.h, but doesn't have a public documentation.

The rest of the documentation keeps using the methods as before, so my guess is this is an omission in the documentation. I.e. the methods (mostly) aren't going anywhere, they were just reshuffled into several protocols and the documentation team has been slacking off. Try making your delegate object conform to the appropriate protocol, and implement the methods with the signatures from the header file.

Answer 2

Documentation is indeed a mess, although looking at the changelog from 4.3 to 5.0 for NSURLConnection.h:

Removed

Removed -[NSObject connection:canAuthenticateAgainstProtectionSpace:] Removed -[NSObject connection:didCancelAuthenticationChallenge:] Removed -[NSObject connection:didFailWithError:] Removed -[NSObject connection:didReceiveAuthenticationChallenge:] Removed -[NSObject connection:didReceiveData:] Removed -[NSObject connection:didReceiveResponse:] Removed -[NSObject connection:didSendBodyData:totalBytesWritten:totalBytesExpectedToWrite:] Removed -[NSObject connection:needNewBodyStream:] Removed -[NSObject connection:willCacheResponse:] Removed -[NSObject connection:willSendRequest:redirectResponse:] Removed -[NSObject connectionDidFinishLoading:] Removed -[NSObject connectionShouldUseCredentialStorage:] Removed NSObject(NSURLConnectionDelegate) 

Added

Added -[NSURLConnection currentRequest] Added -[NSURLConnection originalRequest] Added +[NSURLConnection sendAsynchronousRequest:queue:completionHandler:] Added -[NSURLConnection setDelegateQueue:] Added NSURLConnectionDataDelegate Added -[NSURLConnectionDataDelegate connection:didReceiveData:] Added -[NSURLConnectionDataDelegate connection:didReceiveResponse:] Added -[NSURLConnectionDataDelegate connection:didSendBodyData:totalBytesWritten:totalBytesExpectedToWrite:] Added -[NSURLConnectionDataDelegate connection:needNewBodyStream:] Added -[NSURLConnectionDataDelegate connection:willCacheResponse:] Added -[NSURLConnectionDataDelegate connection:willSendRequest:redirectResponse:] Added -[NSURLConnectionDataDelegate connectionDidFinishLoading:] Added NSURLConnectionDelegate Added -[NSURLConnectionDelegate connection:canAuthenticateAgainstProtectionSpace:] Added -[NSURLConnectionDelegate connection:didCancelAuthenticationChallenge:] Added -[NSURLConnectionDelegate connection:didFailWithError:] Added -[NSURLConnectionDelegate connection:didReceiveAuthenticationChallenge:] Added -[NSURLConnectionDelegate connection:willSendRequestForAuthenticationChallenge:] Added -[NSURLConnectionDelegate connectionShouldUseCredentialStorage:] Added NSURLConnectionDownloadDelegate Added -[NSURLConnectionDownloadDelegate connection:didWriteData:totalBytesWritten:expectedTotalBytes:] Added -[NSURLConnectionDownloadDelegate connectionDidFinishDownloading:destinationURL:] Added -[NSURLConnectionDownloadDelegate connectionDidResumeDownloading:totalBytesWritten:expectedTotalBytes:] Added NSURLConnection(NSURLConnectionQueuedLoading) 

So it seems those functions are indeed still there. Just add the protocols to your @interface declaration and you should be good to go.

I tried the new NSURLConnectionDownloadDelegate, be warned that if these methods are present in your delegate, your NSURLConnectionDataDelegate methods will NOT be called.

I also had issue opening the destinationURL, iOS kept telling me the file did not exist although the documentation indicates the file is guaranteed to exist during the method call.