iPhone SDK Tutorial – Using SQL Lite Part II

Welcome to the second part of the tutorial, where we will select a coffee house and display all the coffee it sells (in a table view). We will also be able to select a coffee and see its details in a grouped table view. This is how the application will look like

Welcome to the second part of the tutorial, where we will select a coffee house and display all the coffee it sells (in a table view). We will also be able to select a coffee and see its details in a grouped table view. This is how the application will look like

I do hope this tutorial will answer some of the questions that you have. Do expect a personal email from me sometime soon, answering all the questions that were asked.

In this tutorial

1. Changes from Part I to Part II
2. Loading another table view
3. Creating parametrized queries
4. Creating a grouped table view
5. Reloading data

DetailView and DetailViewController has been deleted. Class Coffee has been renamed to CoffeeHouse and coffees array has been renamed to coffeeHouseArray.

Create a new view called CoffeeView and CoffeeViewController. Place a table view on the CoffeeView and create a variable in the header file of CoffeeViewController to connect to the object on the view. We also need to implement the UITableViewDelegate and UITableViewDataSource protocol, so we can handle the events generated by the table view and let the table view know that this is the datasource.

Set the File’s Owner proxy object class to CoffeeViewcontroller and create your appropirate connections.

We then need to handle the didSelectAtRowIndexPath method in the root view controller to load the coffee view and pass the coffee house information to the coffee view. To pass the coffee house object we create a variable of type CoffeeHouse (name it aCoffeeHouse) in the coffee view controller. We set this variable in the didSelectRowAtIndexPath method. We implement the set method for this variable, where we first assign the value to the local variable and then get the list of coffees for the coffee house and add it to the array.

Our setACoffeeHouse will look something like this

setACoffeeHouse calls a method getListOfAllCoffeesForThisCoffeeHouse which takes an int. We now query the database to get all the coffee’s for a coffee house. Since compile a sql statement is a little costly we will reuse the compiled statement by creating a static variable of type sqlite3_stmt and use the following sql string “select id, coffeename, size, price, contents from coffee where coffeehouseid=?” to prepare the statment. We will substitute the ? with the coffeehouseid parameter using the sqlite3_bind_int method. We have to remember that parameters in sql start from 1 and not 0 like the array in objective-c. The rest is simple, we get the data from the columns and create a new object of type coffee detail, set all its values and add it to the array.

We now tell the table view how many rows to expect by returning the count of the array. Next thing to do is to get the object from the array in cellForRowAtIndexPath and get its coffee name and set the text property of the cell.

Create another view and name it CoffeeData, then add a table view on top of it and change its style to “Grouped”. Save the view and move the nib file under the resources directory. Create another view controller and name it CoffeeDataController and implement the UITableViewDelegate and UITableViewDataSource. Create a variable of type UITableView with which you can connect to the table view object. Set the class to the File’s Owner Proxy object and create all the connections. In the implementation file we need to implement all the methods required. We will use this class to display all the data releated to the coffee.

Befor we display the data, we need to load the coffee data view when a coffee is selected. To do this create a variable of type CoffeeDataController in the header file of the CoffeeViewController and in didSelectRowAtIndexPath method, we will create an instance of the view we will load and add the view to the top of the stack of the navigation controller.

In the implementation file of the CoffeeDataController, instead of returning 1 from numberOfSectionsInTableView method, we will return 4 one section for one of the pieces of data coffeename, prize, size and contents.

We also need some title for the four sections we just created. To add the title, we need to implement another method called titleForHeaderInSection.

The way we display data in cellForRowAtIndexPath becomes a little different as now we have to consider different sections. The NSIndexPath object has a property called section and we can use this property to write the appropriate value to the text property of the cell. cellForRowAtIndexPath method will look like this

We also need to reload the data if teh same view is loaded again, as the second time the view may need to display different data. To do this, we implement the viewWillAppear method and pass the reloadData messaga to the tableView. This will make the tableview call the cellForRowAtIndexPath again. We also set the title of the view here and not in viewdidLoad method, so the title of the view reflects the coffee selected. This is how the method will look like

This concludes the second part of this tutorial. In the third part of the tutorial, you will learn how too /add/edit/delete the data.

You can download the source code by clicking here. Please do let me know if you found this article helpful or not and what I can I do in future.

I would also like to apologize because it is obvious by now, I did not have a plan on how I will write this tutorial and it has become quite complicated, I think.