Problem using a SQLite database on Xcode - iphone

Question

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 want 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.

Answer 1

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.