Delegate not working (Restkit related?) - iphone

Question

I'm just getting started with Objective C and Restkit
I created a sample application and added the RKRequestDelegate in MyAppDelegate file
#interface MyAppDelegate : NSObject <UIApplicationDelegate, RKRequestDelegate> {…
and added
RKClient* client = [RKClient clientWithBaseURL:#"http://localhost:3000"];
NSLog(#"I am your RKClient singleton : %#", [RKClient sharedClient]);
[client get:#"/titles.json" delegate:self];
to MyAppDelegate.m in the
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions method
I also added a method to MyAppDelegate.m
- (void) request: (RKRequest *) request didLoadResponse: (RKResponse *) response {
if ([request isGET]) {
NSLog (#"Retrieved : %#", [response bodyAsString]);
}
}
so far so good everything is working and I see the results from my Rails app in the output!!!
As those things don't belong into MyAppDelegate.m I'm moving that stuff into my models. In my Titles.h I added
#interface Titles : NSManagedObject <RKRequestDelegate> {
and in Titles.m I added
+ (void) update {
[[RKClient sharedClient] get:#"/titles.json" delegate:self];
}
and
- (void) request: (RKRequest *) request didLoadResponse: (RKResponse *) response {
if ([request isGET]) {
NSLog (#"Retrieved : %#", [response bodyAsString]);
}
}
In my MyAppDelegate.m I replaced :
RKClient* client = [RKClient clientWithBaseURL:#"http://localhost:3000"];
NSLog(#"I am your RKClient singleton : %#", [RKClient sharedClient]);
[client get:#"/titles.json" delegate:self];
with
RKClient* client = [RKClient clientWithBaseURL:#"http://localhost:3000"];
NSLog(#"I am your RKClient singleton : %#", [RKClient sharedClient]);
[Titles update];
when I run now I don't get any output.
I put several breakpoints, one in the - (void)didFinishLoad:(RKResponse*)response in the RKRequest file
and there the if test for :
if ([_delegate respondsToSelector:#selector(request:didLoadResponse:)]) {
[_delegate request:self didLoadResponse:finalResponse];
}
fails while it succeeds in my first attempt (when everything is in MyAppDelegate)
I checked the variable _delate in de debugger and it says: _delegate = MyAppDelegate in my first attempt and _delegate = Titles in my second attempt (both like it should)
Why does that respondsToSelector fail ? (the delegate is correct and the method exists in Titles)

Answer 1

Your problem is that your trying to set a class as the delegate:
+ (void) update {
[[RKClient sharedClient] get:#"/titles.json" delegate:self];
}
self here is the class Titles.
The callback is (as expected), an instance method:
- (void) request: (RKRequest *) request didLoadResponse: (RKResponse *) response {
if ([request isGET]) {
NSLog (#"Retrieved : %#", [response bodyAsString]);
}
}
You should have some kind of "DataModel" model class (perhaps "SongList" or whatever makes sense). This is often a singleton, so you have a +sharedModel instance. That instance is what is the delegate for RKClient.