显示内存泄漏

Question

我是iphone的新手。我有一部分代码显示100％内存泄漏。为什么这会显示内存泄漏。我知道我已经释放了我的对象。 源代码：

Database_Methods *da=[[Database_Methods alloc] init];
    self.newsArr=[da getNews:tableid];
    [da release];

- (NSMutableArray *) getNews:(NSInteger )tableid { 
    NSString *tableName=[NSString stringWithFormat:@"Table%d",tableid]; 
    NSMutableArray * categoryArray = [[NSMutableArray alloc] init]; 

    @try { 
        NSFileManager *fileManager = [NSFileManager defaultManager]; 
        NSArray * paths = NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES);


        NSString * docsDir = [paths objectAtIndex:0]; 
        NSString * theDBPath = [docsDir stringByAppendingPathComponent: @"Training_Project2.sqlite"];
        BOOL success = [fileManager fileExistsAtPath:theDBPath]; 

        if (!success) { 
            NSLog(@"Failed to find database file '%@'.",theDBPath); 
        } 

        if (!(sqlite3_open([theDBPath UTF8String], &database) == SQLITE_OK)) {

             NSLog(@"An error opening database, handle error here."); 
        } 

        NSString *query=[NSString stringWithFormat:@"SELECT link,flag,title FROM %@ order by rowid desc",tableName]; 
        const char *sql = [query UTF8String]; 
        sqlite3_stmt *statement; 

        if (sqlite3_prepare_v2(database, sql, -1, &statement, NULL) != SQLITE_OK) { 
            NSLog(@"Error, failed to prepare statement, handle error here."); 
        }


        while (sqlite3_step(statement) == SQLITE_ROW) { 
            NewsRss * aCategory = [[NewsRss alloc] init]; 

            //aCategory.categoryid = sqlite3_column_int(statement, 0); 
            aCategory.link = [NSString stringWithUTF8String:(char *)sqlite3_column_text(statement, 0)]; 
            aCategory.flag = sqlite3_column_int(statement, 1); 
            aCategory.title=[NSString stringWithUTF8String:(char *)sqlite3_column_text(statement, 2)]; 
            [categoryArray addObject:aCategory]; 
            [aCategory release]; 
        }