UITableView custom class huge leak - iphone

Question

I am using a custom class to display some info on a table view.
The problem is that as long as I scroll the tableview memory is leaking...
I guess I have something wrong at my class.
Please have a look:
#interface Person : NSObject {
NSString *name;
NSString *surname;
NSString *address;
NSString *email;
}
#property (nonatomic, copy) NSString *name, *surname, *address, *email;
#implementation Person
#synthesize name, surname, address, email;
-(id)init {
[super init];
name = [[NSString alloc] init];
surname = [[NSString alloc] init];
address = [[NSString alloc] init];
email = [[NSString alloc] init];
return self;
}
- (void)dealloc
{
[name release];
[surname release];
[address release];
[email release];
[super dealloc];
}
#import "Person.h"
#interface Group : NSObject {
NSString *groupTitle;
NSMutableArray *persons;
}
#property (readwrite, copy) NSString *groupTitle;
- (void)addPerson:(Person *)person;
- (void)removeAll;
- (NSArray *)getPersons;
- (int)PersonsCount;
#end
#implementation Group
#synthesize groupTitle;
-(id)init {
[super init];
persons = [[NSMutableArray alloc] init];
return self;
}
-(void)addPerson:(Person *)person {
[persons addObject:person];
}
-(void)removeAll {
[persons removeAllObjects];
}
-(NSArray *) getPersons {
return [persons copy];
[persons release];
}
-(int)personsCount {
return [persons count];
}
-(void)dealloc {
[groupTitle release], groupTitle = nil;
[persons release], persons = nil;
[super dealloc];
}
#end
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
…….
Group *groupForRow = [[Group alloc] init];
Person *personForRow = [[Person alloc] init];
personForRow = [[groupForRow getPersons] objectAtIndex:indexPath.row];
_personName = personForRow.name;
_personSurname = personForRow.surname;
_personAddress = personForRow.address;
_personEmail = personForRow.email;
[groupForRow release], groupForRow = nil;
[personForRow release], personForRow = nil;
…..
return cell

Answer 1

Few corrections (read the comments):
#interface Person : NSObject {
NSString *name;
NSString *surname;
NSString *address;
NSString *email;
}
// copy is OK for strings...
#property (nonatomic, copy) NSString *name, *surname, *address, *email;
#end
#implementation Person
#synthesize name, surname, address, email;
- (id)init {
if (self = [super init]) {
// There is no need to allocate the strings
// In addition, once you write 'name = [[NSStrin alloc] init];' you don't use the property.
// If you do want to use the property setter then you should write 'self.name = #"some string";'
}
return self;
}
- (void)dealloc {
[name release];
[surname release];
[address release];
[email release];
[super dealloc];
}
#end
#import "Person.h"
#interface Group : NSObject {
NSString *groupTitle;
NSMutableArray *persons;
}
// Any special reason for "readwrite" instead of "nonatomic"?
#property (readwrite, copy) NSString *groupTitle;
// This property is more important than the string:
#property (nonatomic, retain) NSMutableArray *persons;
- (void)addPerson:(Person *)person;
- (void)removeAll;
- (NSArray *)getPersons;
- (int)PersonsCount;
#end
#implementation Group
#synthesize groupTitle, persons;
- (id)init {
if (self = [super init]) {
// Use the autoreleased array instance ([NSMutableArray array]) and set it to the property setter that will retain the object:
self.persons = [NSMutableArray array];
}
return self;
}
- (void)addPerson:(Person *)person {
// I prefer using properties (the "self." in the beginning) instead of the members directly...
[self.persons addObject:person];
}
- (void)removeAll {
[self.persons removeAllObjects];
}
// I think that this getter is unnecessary - use the property instead...
- (NSArray *) getPersons {
// There is no need to copy
return [persons copy];
// Don't you have a warning for this line? It is never executed
[persons release];
}
- (int)personsCount {
return [self.persons count];
}
- (void)dealloc {
[groupTitle release], groupTitle = nil;// The "groupTitle = nil" is unnecessary.
[persons release], persons = nil;// The "persons = nil" is unnecessary.
[super dealloc];
}
#end
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
…….
Group *groupForRow = [[Group alloc] init];// Do you REALLY have to allocate this object each "cellForRowAtIndexPath"??
Person *personForRow = [[Person alloc] init];// Get rid of the "= [[Person alloc] init]" - this is a leak (because of the next line)
personForRow = [[groupForRow getPersons] objectAtIndex:indexPath.row];// If you will use the property persons instead of the "getPersons" (that copies the array) then you will get rid of another leak
// What are these?
_personName = personForRow.name;
_personSurname = personForRow.surname;
_personAddress = personForRow.address;
_personEmail = personForRow.email;
// The " = nil" is unnecessary here...
[groupForRow release], groupForRow = nil;// If you won't allocate the group then you won't need this line...
[personForRow release], personForRow = nil;// NSZombie - you release object that you don't owe (do you have crashes, that you don't know why they are happen?)
…..
return cell;
}

Answer 2

There is a lot wrong here, please delve a little into objective-C to get a grasp of the use of #property and #synthesize to get correctly functioning getter/setter methods.
As for your memory leak when scrolling, it is caused by the allocs in cellForRowAtIndexPath which are not balanced by either a release or an autorelease.
This:
Group *groupForRow = [[[Group alloc] init] autorelease];
Person *personForRow = [[[Person alloc] init] autorelease];
should fix most of your leaks. Browse around on SO for more info.