What is the source of the leaky object for this code?

Question

Anyone able to help re what is the source of the leaky object for this code:

My application compiles without any ANALYZE issues. When I run PROFILER and look at Memory Leaks I see leaks appears. One of these leaks is in my WeekendEvent object. There are 3 Leaked Block row items in instruments per the below (I've noted in the code where these point to):

• Malloc +1
• Retain +2
• Release +1

Question - I assume this implies there is a release, however where would this leak be from. The segments of my code that clicking through on instruments highlights is below. To me it seems OK in that:

1. the WeekendEvent I create I release after passing into the addWeekendEvent method
2. in the addWeekendEvent it just adds it to a NSMutableArray, and hence I thought the arrange does any memory management for it's object it contains
3. I do release the NSMutableArray in the dealloc too

Key Source Code Bits & What Instuments Highlights

// ------Weekends Method (plural)-----
WeekendEvent *weEvent = [[WeekendEvent alloc] init]; // [INSTRUMENTS - 87.5%]
[week addWeekendEvent:weEvent];                      // [INSTRUMENTS - 12.5%]
[weEvent release];                  


//------Weekend *.h ------------
@interface Weekend : NSObject {
    NSMutableArray*     _events;     
}
- (void)addWeekendEvent:(WeekendEvent*)weEvent;
@property (nonatomic, retain) NSMutableArray* events;
@end


//------Weekend *.m -------------
- (void)addWeekendEvent:(WeekendEvent*)weEvent {
    [self.events addObject:weEvent];
}
- (void) dealloc {
    [_events release];
    [super dealloc];
}

EDIT: Some additional code re how the "week" variable above was created/used - so in the Weekends Method the code I posted was within a for loop - the code with the for loop shown therefore was:

for (Weekend *week in self.items) {
   // do pass "week.start" to some methods (which is an NSDate) - don't think this would be relevant though?
   WeekendEvent *weEvent = [[WeekendEvent alloc] init]; // [INSTRUMENTS - 87.5%]
   [week addWeekendEvent:weEvent];                      // [INSTRUMENTS - 12.5%]
   [weEvent release];   
}               
// Note - self.items I checked is "released" in the dealloc method

EDIT 2 - Just to confirm, it is an "WeekendEvent" instance that Instruments highlights in it's "leaked objects" column. Just in case this wasn't clear.

EDIT 3 - Re how I setup the items variable - key code bits are:

@interface Weekends : NSObject {
    NSMutableArray* _items;
}
@property (nonatomic, retain) NSMutableArray* items;

@synthesize items = _items;
- (void) dealloc {
    [_items release];
    [super dealloc];
}

Answer 1

The memory management in the code you show is correct, assuming that the rest of your Weekend class looks something like this:

@synthesize events = _events;

- (id)init {
    if ((self = [super init]) == nil) { return nil; }
    _events = [[NSMutableArray alloc] initWithCapacity:0];
    return self;
}

Also, the instruments results match all of your code:

Malloc  +1  ==  WeekendEvent *weEvent = [[WeekendEvent alloc] init];
Retain  +2  ==  [week addWeekendEvent:weEvent];
Release +1  ==  [weEvent release];

Based on that logic, the most likely candidate is that your week object is not properly released. You haven't shown the code that explains how it was created, but I do notice that the code you did post is for a Weekend class. Are you sure week is not of a different type?