Subclassing NSURLConnection for authentication? - ios

Question

I have a subclass:
#import <Foundation/Foundation.h>
#interface CustomURLConnection : NSURLConnection <NSURLConnectionDelegate>
#end
In it's implementation file i have the following function:
-(void) connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge
{
NSLog(#"Authenticating from subclass.");
}
note that didReceiveAuthenticationChallenge is part of NSURLConnectionDelegate
This snippet is currently in every class that sends a NSURLRequest using NSURLConnection:
-(void) connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge
{
// Code to authenticate ourselves.
}
The actual problem:
I want the subclass to have a predetermined behaviour for
connection:(CustomURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge
instead of having to implement the function in every class. And instead have every class use the subclass instead and have every authentication challenge handled automatically by the subclass.
The class is allocated as follows:
cUrlConnection = [[CustomURLConnection alloc]initWithRequest:req delegate:self startImmediately: YES];
if (cUrlConnection)
{
// Handle events when connection is active.
}
If anyone has any insight in how i make my CustomURLConnection handle the authentication mechanism and/or tips/pointers i'd be delighted.

Answer 1

It's a somewhat awkward pattern, but what you want to do in the subclass is take over the delegate setting/getting and the provide a different, private-implementation delegate to the superclass that implements this method the way you want and passes all the other methods to the user-supplied delegate. (Note: since NSURLConnection takes its delegate at init-time, there's no -delegate and -setDelegate: methods to override. This is untested, but it might look something like this:
#interface MyCustomURLConnection : NSURLConnection
#end
#interface MyPrivateImpDelegate : NSObject
- (id)initWithRealDelegate: (id<NSURLConnectionDelegate>)realDel;
#end
#implementation MyPrivateImpDelegate
{
__weak id<NSURLConnectionDelegate> _userDelegate;
}
- (id)initWithRealDelegate:(id<NSURLConnectionDelegate>)realDel
{
if (self = [super init])
{
_userDelegate = realDel;
}
return self;
}
- (void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge
{
// Your auth implementation here...
// maybe call through if you want?
if ([_userDelegate respondsToSelector: _cmd])
{
[_userDelegate connection:connection didReceiveAuthenticationChallenge:challenge];
}
}
- (id)forwardingTargetForSelector:(SEL)aSelector
{
return _userDelegate;
}
- (BOOL)respondsToSelector:(SEL)aSelector
{
BOOL retVal = [super respondsToSelector: aSelector];
if (!retVal)
{
retVal = [_userDelegate respondsToSelector: aSelector];
}
return retVal;
}
#end
#implementation MyCustomURLConnection
{
MyPrivateImpDelegate* _fakeDelegate;
}
- (id)initWithRequest:(NSURLRequest *)request delegate:(id)delegate startImmediately:(BOOL)startImmediately
{
MyPrivateImpDelegate* privDel = [[MyPrivateImpDelegate alloc] initWithRealDelegate: delegate];
if (self = [super initWithRequest:request delegate:privDel startImmediately:startImmediately])
{
_fakeDelegate = privDel; // make sure our private delegate lives as long as we do.
}
return self;
}
- (void)dealloc
{
_fakeDelegate = nil;
}
#end