ios - Potential Leak of an Object that is released before reuse and dealloc'd on exit -

using xcode analyzer, getting warning potential leak of object. warning perplexing , need explanation why getting error. here code in mediasources hold pointer object in question:

in .h file, pointer mediasources class created , given retain property:

@interface rootviewcontroller : uiviewcontroller <...> {     ...      mediasources                *mediasources;      ... }  @property (nonatomic, retain)   mediasources            *mediasources; 

in .m file (rootviewcontroller) method can called many times. consequently, release object on each entry , alloc new object. mediasources object performs background tasks, don't want release until know complete. if use autorelease on line class alloc'd in, crashes. :

-(void) getselectedmediasources {     [self setmediasources: nil];    // release old stuff , nilify      [self setmediasources: [[mediasources alloc] init]];      [self.mediasources checkformediasourceupdates]; } 

also in .m file, mediasources synthesized , released in dealloc

@synthesize mediasources;  ...  - (void)dealloc {     ...     [mediasources release];     ...      [super dealloc]; } 

please explain why getting warning. don't see how there leak. dealloc should release last copy of object.

in response request code checkformediasourceupdates. going bit complicated, below essence:

(void) checkformediasourceupdates {         nsstring *s = [nsstring  stringwithformat:@"http://www.mywebsite.com/mediasources/%@/mediasources.plist", countrycode];      nsurl *url = [nsurl urlwithstring:s];     nsurlrequest *req = [nsurlrequest requestwithurl:url  cachepolicy:nsurlrequestreloadignoringlocalandremotecachedata timeoutinterval:60.0];     mydownloader *d = [[mydownloader alloc] initwithrequest:req];     [self.connections addobject:d];     [[nsnotificationcenter defaultcenter] addobserver:self  selector:@selector(checkformediasourceupdatesdownloadfinished:) name:@"connectionfinished" object:d];     [d.connection start];     [d release]; }  -(void) checkformediasourceupdatesdownloadfinished: (nsnotification *) n  {     mydownloader *d = [n object];     nsdata *data = nil;     if ([n userinfo]) {         nslog(@"in checkformediasourceupdatesdownloadfinished: mydownloader returned error");     }     else {         data = [d receiveddata];          // data     } } 

the mydownloader class performs download of file specified in input nsurlrequest. after completing download, class generate nsnotification named "connectionfinished". user of class must register notification , handle cleanup operations of class. if download fails, class generate nsnotification, named "connectionfinished", addition of userinfo indicates error occured. again, user of class must register notification , handle cleanup operations of class.

per definition pass autoreleased object synthesized setter. setter retains object, following line wrong:

[self setmediasources: [[mediasources alloc] init]];  

it should be:

[self setmediasources: [[[mediasources alloc] init] autorelease]];  

also not need call setter nil before. when setting different object via setter, old object gets released. synthesized setter looks like:

- (void) setmediasources:(mediasources *)mediasources {   if (_mediasources != mediasources) {     [_mediasources release];     _mediasources = [mediasources retain];   } } 

the question is: why need allocate new mediasource on every call getselectedmediasources? crash expecting when deallocating autoreleased mediasource? setting delegate object or registering nsnotificationcenter? if so, not forget nil out delegate or remove notification center.