NSURLConnection in NSOperation - objective-c

Question

I am writing a code that reads data from a http connection and stores in a byte array.
I have written my own NSOperation class. Reference of the code is
Concurrent Operations Demystified
My HttpWorker class declaration is like
#interface HttpWorker : NSOperation{
NSString *param;
double requestCode;
BOOL isLive;
long initSleep;
BOOL _isFinished;
BOOL _isExecuting;
NSURL *_url;
NSURLConnection *_connection;
NSData *_data;
}
#property (nonatomic, retain) NSString *param;
#property (nonatomic) double requestCode;
#property (nonatomic) BOOL isLive;
#property (nonatomic) long initSleep;
#property (readonly) BOOL isFinished;
#property (readonly) BOOL isExecuting;
#property (readonly, copy) NSURL *url;
#property (nonatomic, retain) NSURLConnection *httpCon;
#property (readonly, retain) NSData *data;
-(id)initWithUrl:(NSURL *)_url;
-(void) setRequestParameters:(NSString *)parameters iRequestCode:(double)iRequestCode initialSleep:(long)initialSleep;
#end
And my HttpWorker.m class is like
#import "HttpWorker.h"
#import "Resources.h"
#implementation HttpWorker
#synthesize param;
#synthesize requestCode;
#synthesize isLive;
#synthesize initSleep;
#synthesize isFinished = _isFinished;
#synthesize isExecuting = _isExecuting;
#synthesize url = _url;
#synthesize data = _data;
-(id) initWithUrl: (NSURL *)Url{
self = [super init];
if(self == nil){
return nil;
}
_url = [Url copy];
_isExecuting = NO;
_isFinished = NO;
return self;
}
-(BOOL) isConcurrent{
return YES;
}
-(void) start{
if(![NSThread isMainThread]){
[self performSelectorOnMainThread:#selector(start) withObject:nil waitUntilDone:NO];
return;
}
[self willChangeValueForKey:#"isExecuting"];
_isExecuting = YES;
[self didChangeValueForKey:#"isExecuting"];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:_url];
NSLog(#"Connecting... %#",_url);
_connection = [[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately: YES];
if(_connection == nil){
NSLog(#"connection is nil");
}
}
-(void) setRequestParameters:(NSString *)parameters iRequestCode:(double)iRequestCode initialSleep:(long)initialSleep {
self.param = parameters;
self.requestCode = iRequestCode;
self.initSleep = initialSleep;
}
/////////////////////////// delegate methods ///////////////////////////////
-(void) connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
NSLog(#"receieved response...");
_data = [[NSData alloc] init];
}
-(void) connection:(NSURLConnection *)connection didReceiveData:(NSData *)incomingData {
NSLog(#"receieved data...");
}
-(void) connectionDidFinishLoading:(NSURLConnection *) connection {
NSLog(#"connection did finish loading...");
}
#end
Problem is that when i run this code and add httpworker object to the NSOperationQueue, the code runs successfully and _connection is not nil but none of the delegate methods is executed. Can anyone please help?
Thanks and Best Regards...

Answer 1

Your delegate for the connection is "self" (= your NSOperation object). I assume this object is already gone when the connection wants to send messages to the delegate.
Your NSOperation does not have a "main" implementation. Consequently nothing will happen after the thread is started. It will (asynchronously!) fire the NSOperation and quit.
See:
http://developer.apple.com/mac/library/documentation/Cocoa/Reference/NSOperation_class/Reference/Reference.html#//apple_ref/occ/instm/NSOperation/main
Bottom line: I highly recommend ASIHTTPRequest for this kind of task.
http://allseeing-i.com/ASIHTTPRequest/