Question

I’m currently battling through some memory leaks and having some serious trouble working out one of the last ones I have left. The leaks instrument shows several leaks all coming from the same method for various different reasons mostly attributed to either NSCFString, NSMutableArray and a class I made called GraphData. I have attempted to fix it in a few different ways to no avail so hopefully some light can be shed on this problem which hopefully is something simple I have overlooked.

Here is some code:

// the offending, leaking method
-(NSMutableArray*)fillDataInArray:(NSInteger)keyphrase_id{

    NSLog(@"Keyphrase_id:%d", keyphrase_id);

    NSDate *startdate = [self getDateForApplicationInstalled];
    NSDate *enddate = [NSDate date];

    NSString *dateString1=[[NSString alloc] initWithString: [fmt stringFromDate:startdate]];
    NSString *dateString2=[[NSString alloc] initWithString: [fmt stringFromDate:enddate]];

    NSMutableArray *newDataNew = [[NSMutableArray alloc]init];
    self.newData = newDataNew;
    [newDataNew release];

    selStmt = nil;

    if (!selStmt)
    {
        const char *sql = "select distinct position, key_time from ranking where keyphrase_id = ? and key_time between ? and ? order by key_time";

        if (sqlite3_prepare_v2(database, sql, -1, &selStmt, NULL) != SQLITE_OK)
        {
            selStmt = nil;
        }

        NSInteger n = keyphrase_id;
        sqlite3_bind_int(selStmt, 1, n);

        sqlite3_bind_text(selStmt, 2, [dateString1 UTF8String] , -1, SQLITE_TRANSIENT);
        sqlite3_bind_text(selStmt, 3, [dateString2 UTF8String] , -1, SQLITE_TRANSIENT);

        NSLog(@"SQL query is: [%s]", sql);
    }
    if (!selStmt)
    {
        NSAssert1(0, @"Can't build SQL to read keyphrases [%s]", sqlite3_errmsg(database));
    }

    int ret;

    while ((ret=sqlite3_step(selStmt))==SQLITE_ROW) 
    { 
        GraphData *item = [[GraphData alloc]init];

        item.key = sqlite3_column_int(selStmt, 0);
        item.value = [NSString stringWithUTF8String:(char *)sqlite3_column_text(selStmt,1)];

        [newData addObject:item]; 

        [item release], item = nil;
    }

    sqlite3_reset(selStmt); // reset (unbind) statement

    [dateString2 release];
    [dateString1 release];

    return newData;
}

//GraphData.h
@interface GraphData : NSObject{
    NSInteger key;
    NSString *value;
}

@property (nonatomic, readwrite) NSInteger key;
@property (nonatomic, retain) NSString *value;

-(id)initWithPrimaryKey:(NSInteger) xid;
-(id)initWithName:(NSString *)n key:(NSInteger)i;

@end

//GraphData.m
#import "GraphData.h"

@implementation GraphData

@synthesize  key,value;

-(id)initWithPrimaryKey:(NSInteger) xid{

    self.key = xid;
    self.value = @"";

    return self;

}
-(id)initWithName:(NSString *)n key:(NSInteger)i{

    self.key = 0;
    self.value = n;

    return self;

}
-(void)dealloc{


    [value release], value = nil;
    [super dealloc];

}

@end

Thanks for looking at my post!

Answer 1

the leak tool tells you where a leaked object has been created. As NSCFString, NSMutableArray and GraphData objects are leaked from this method, let’s have a look how this could happen.

You insert GraphData objects (containing string objects) only in an NSMutableArray and they seem to be properly released. So to leak a GraphData object that is created inside this method, the array containing the elements has to be the leak.

Please check the callers of the method. I assume one of them is retaining (and not releasing) the return value of the method.

Also, your initializers have to be changed to call super’s init, but this is not related to the leak. An example:

-(id)initWithPrimaryKey:(NSInteger) xid
{
    self = [super init];
    if (self) {
        self.key = xid;
        self.value = @"";
    }
    return self;   
}