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POReference counting when implementing a delegate for custom class in ObjectiveC
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copied!<p>I have two classes, ClassA that will instantiate ClassB and pass off a method as a delegate. ClassB will eventually invoke ClassA's delegate. Do I need to add a retain on ClassA when ClassB stores it?</p> <p>I'm following the "Implementing a Delegate for a Custom Class" from the "Cocoa Fundamentals Guide: Communicating with Objects" but the sample code demonstrated doesn't seem to take memory management into account.</p> <p>ClassA will set the delegate and expect to be called back later when ClassB is done with it's work.</p> <pre><code>@implementation ClassA -(void)launchSomething { ClassB *classB = [[ClassB alloc] init]; [classB setCallback:self withSelector:@selector(deferredWork)]; // do some other stuff, assign class B to some View and eventually release class B } -(void)deferredWork { NSLog(@"this is the method that will be deferred till some point in time"); } </code></pre> <p>Header file for the ClassB that'll store and then later invoke the delegate:</p> <pre><code>@interface ClassB id targetObject; SEL targetMethod; -(void) setCallback:(id)anObject withSelector:(SEL)aMethod </code></pre> <p>ClassB's implementation:</p> <pre><code>@implementation ClassB -(void) setCallback:(id)anObject withSelector:(SEL)aMethod { // QUESTION: Do I need to add a 'retain' here on the targetObject? targetObject = anObject; targetMethod = aMethod; } -(void) someWorkLater { if ( [targetObject respondsToSelector:@selector(targetMethod)] ) { // invoke the target object with the specific method [targetObject targetMethod]; } } </code></pre>

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