Problem using a SQLite database on Xcode

I'm quite new to Xcode and I have a huge problem with a tutorial I'm working on.

I'm trying to write a simple shopping list, using a sql database.

Actually i finished with the project. I triple checked every single line of code, but for some reason it doesn't wa开发者_C百科nt to show me the content of the DB nor write something inside.

Really I have no idea what's wrong with the code... Writing in the DB:

-(IBAction)addShoppingListItem:(id)sender {
//apriamo il database
if (([itemNameField.text length] == 0) || ([priceField.text length] == 0) || ([priceField.text doubleValue] == 0.0)) {
    return;
}
sqlite3 *db;
int dbrc; //Codice di ritorno del database (database return code)
DatabaseShoppingListAppDelegate *appDelegate = (DatabaseShoppingListAppDelegate*) [UIApplication sharedApplication].delegate;
const char *dbFilePathUTF8 = [appDelegate.dbFilePath UTF8String];
dbrc = sqlite3_open(dbFilePathUTF8, &db);
if (dbrc) {
    NSLog(@"Impossibile aprire il Database!");
    return;
}
//database aperto! Inseriamo valori nel database.
sqlite3_stmt *dbps; //Istruzione di preparazione del database
NSString *insertStatementsNS = [NSString stringWithFormat: @"insert into \"shoppinglist\" (item, price, groupid, dateadded) values (\"%@\", %@, %d, DATETIME('NOW'))", name_field, price_field, [groupPicker selectedRowInComponent:0]];
const char *insertStatement = [insertStatementsNS UTF8String];
dbrc = sqlite3_prepare_v2(db, insertStatement, -1, &dbps, NULL);
dbrc = sqlite3_step(dbps);
//faccio pulizia rilasciando i database
sqlite3_finalize(dbps);
sqlite3_close(db);

// Pulisci i campi e indica successo nello status
statusLabel.text = [[NSString alloc] initWithFormat: @"Aggiunto %@", itemNameField.text];
statusLabel.hidden = NO;
itemNameField.text = @"";
priceField.text = @"";
}

Loading from the database:

-(void)loadDataFromDb {
//apriamo il database
sqlite3 *db;
int dbrc; //Codice di ritorno del database (database return code)
DatabaseShoppingListAppDelegate *appDelegate = (DatabaseShoppingListAppDelegate *) [UIApplication sharedApplication].delegate;
const char *dbFilePathUTF8 = [appDelegate.dbFilePath UTF8String];
dbrc = sqlite3_open(dbFilePathUTF8, &db);
if (dbrc) {
    NSLog(@"Impossibile aprire il Database!");
    return;
}
//database aperto! Prendiamo i valori dal database.
sqlite3_stmt *dbps; //Istruzione di preparazione del database
NSString *queryStatementNS = @"select key, item, price, groupid, dateadded from shoppinglist order by dateadded";
const char *queryStatement = [queryStatementNS UTF8String];
dbrc = sqlite3_prepare_v2(db, queryStatement, -1, &dbps, NULL);

//Richiamo la funzione sqlite3_step() finché ho righe nel database
while ((dbrc = sqlite3_step(dbps)) == SQLITE_ROW) {
    int primaryKeyValueI = sqlite3_column_int(dbps, 0);
    NSNumber *primaryKeyValue = [[NSNumber alloc] initWithInt:primaryKeyValueI];
    NSString *itemValue = [[NSString alloc] initWithUTF8String:(char*) sqlite3_column_text(dbps, 1)];
    double priceValueD = sqlite3_column_double(dbps, 2);
    NSNumber *priceValue = [[NSNumber alloc] initWithDouble:priceValueD];
    int groupValueI = sqlite3_column_int(dbps, 3);
    NSNumber *groupValue = [[NSNumber alloc] initWithInt:groupValueI];
    NSString *dateValueS = [[NSString alloc] initWithUTF8String:(char*) sqlite3_column_text(dbps, 4)];
    NSDate *dateValue = [dateFormatter dateFromString: dateValueS];

    NSMutableDictionary *rowDict = [[NSMutableDictionary alloc] initWithCapacity:5];
    [rowDict setObject:primaryKeyValue forKey: ID_KEY];
    [rowDict setObject:itemValue forKey: ITEM_KEY];
    [rowDict setObject:priceValue forKey: PRICE_KEY];
    [rowDict setObject:groupValue forKey: GROUP_ID_KEY];
    [rowDict setObject:dateValue forKey: DATE_ADDED_KEY];
    [shoppingListItems addObject: rowDict];

    //rilascio tutti gli elementi
    [dateValue release];
    [primaryKeyValue release];
    [itemValue release];
    [priceValue release];
    [groupValue release];
    [rowDict release];
}
}

For the brave who wants to check all the project (there is just another class) here there is the link with all my work. http://www.mediafire.com/?qxfde723r29nhtb

Thanks in advance.

You have too many mistakes in your code. Let's briefly look at them:

1) In your application delegate you place db initialization code in applicationDidFinishLaunching method, but according to Apple's manuals:

This method is used in earlier versions of iOS to initialize the application and prepare it to run. In iOS 3.0 and later, you should use the application:didFinishLaunchingWithOptions: instead.

so, I just moved initializeDb method into - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions

2) In ListViewController you have a method loadDataFromDb but I didn't find its usage. You never call this method. In the same controller you have viewWillAppear method that I used to initialize your shoppingListItems array that will be shown in tableView as follows:

-(void)viewWillAppear:(BOOL)animated {
    shoppingListItems = [[NSMutableArray alloc] init];
    [self loadDataFromDb];
    [tableView reloadData];
}

tableView is a outlet to UITableView control that you place in your nib file. I added its declaration in ListViewController.h:

@interface ListViewController : UIViewController {
    UITableViewCell *nibLoadedCell;
    IBOutlet UITableView *tableView;
}
@property(nonatomic, retain) IBOutlet UITableViewCell *nibLoadedCell;

@end

and bind in interface builder with the actual control.

3) AddItemViewController's method addShoppingListItem didn't work because didn't pass this condition:

if (([itemNameField.text length] == 0) || ([priceField.text length] == 0) || ([priceField.text doubleValue] == 0.0)) {
        return;
    }

You didn't bind your outlets in interface builder for itemNameField, priceField, groupPicker.

By fixing this I got working solution, but actually I didn't check memory usage and suppose you have also some problem in memory management here.