Question

I have a query regarding the memory management.

Let’s begin with an example. Assume we have a class as follows.

@interface myClass : NSObject {
    NSString *xyz;
}
@end

Now, see the implementation.

@interface myClass : NSObject {
    NSString *xyz;
}
@end

@implementation myClass
-(void)abc{
    // xyz allocted here
}
-(void)pqr{
    // retained or copied many times or may not a single time
}
-(void)mno{
    // retained or copied many times or may not a single time
}
-(void)jpg{
    // may be released more than one time or may be not
}


//-(void)dealloc{
//  [xyz release];
//  [super dealloc];
//}
//
//-(void)dealloc{
//  if(xyz!=nil && [xyz retainCount]>0){ [xyz release]; xyz=nil; }
//  [super dealloc];
//}

-(void)dealloc{
    if(xyz!=nil){ 
        while([xyz retainCount]>0) 
           [xyz release]; 
        xyz=nil; 
    }
    [super dealloc];
}
@end

In above code. I have three dealloc functions. Which one is preferable? If none of these, then please suggest yours.

I am confused because Objective C says, object must be released each time = each time alloc/retained.

But most of the sample code has just single statement “[xyz release];” doesn’t it create a memory leak?

Answer 1

- (void)dealloc {
    [xyz release];
    [super dealloc];
}

…is the correct version. In Objective-C, you generally shouldn’t use the retainCount method.

If you want to be very safe, you can also write:

- (void)dealloc {
    [xyz release], xyz = nil;
    [super dealloc];
}