Memory management has me confused again --
In my .h file, I have:
@property (nonatomic,retain) NSMutableDictionary *properties;
In my .m, I have the following init method, which complains of a leak in Instruments on the self.properties line:
- (id) init {
self = [super init];
self.properties = [[NSMutableDictionary alloc] init];
return self;
}
It also complains of a leak if I don't use the accessor.
Likewise, it leaks if I use this strategy:
NSMutableDictionary *temp = [[NSMutableDictionary alloc] init];
self.properties = temp;
[temp release];
And in dealloc I have:
self.properties = nil;
[properties release];
I thought I was following the rules, but this one is alluding me.
If your .h is defined like this:
@interface MDObject : NSObject {
NSMutableDictionary *properties;
}
@property (nonatomic, retain) NSMutableDictionary *properties;
@end
The following are possible correct implementations of your .m:
@implementation MDObject
- (id)init {
if ((self = [super init])) {
properties = [[NSMutableDictionary alloc] init];
}
return self;
}
- (void)dealloc {
[properties release];
[super dealloc];
}
@end
or
@implementation MDObject
- (id)init {
if ((self = [super init])) {
self.properties = [NSMutableDictionary dictionary];
}
return self;
}
- (void)dealloc {
self.properties = nil; // while this works,
// [properties release] is usually preferred
[super dealloc];
}
@end
It might be helpful to remember that
self.properties = [NSMutableDictionary dictionary];
is the same as
[self setProperties:[NSMutableDictionary dictionary]];
Those 2 methods that are synthesized for you would look similar to the following:
- (NSMutableDictionary *)properties {
return properties;
}
- (void)setProperties:(NSMutableDictionary *)aProperties {
[aProperties retain];
[properties release];
properties = aProperties;
}
If you have @property(retain) then you shouldn't just alloc and then use the accessor because you've over-retained the object. Either release it after you set the property or autorelease it first.
