odunze / journal

Journal (Core Data)

Introduction

This version of Journal will allow you to implement each part of CRUD when working with Core Data. This project is essentially the same as the Journal project you've previously wrote. However, please write this project from scratch. We can't regulate this, but you will undoubtedly learn less if you are copying and pasting past code.

Please look at the screen recording below to know what the finished project should look like:

Instructions

Please fork and clone this repository. This repository does not have a starter project, so create one inside of the cloned repository folder.

Part 1 - Storyboard Layout

This application will implement the Master-Detail pattern that you're surely familiar with by now.

EntriesTableViewController and EntryTableViewCell

1. Delete the view controller scene that comes with the Main.storyboard
2. Add a UITableViewController scene, then embed it in a navigation controller. Set the navigation controller as the initial view controller.
3. Add a UIViewController scene as well. Leave it blank for now.
4. On the table view controller scene, change its navigation item's title to "Journal".
5. Add a bar button item on the right side of the navigation bar. Change its "System Item" to "Add".
6. Create a segue from the bar button item to the blank UIViewController scene. This segue will be used to create new entries. Give it an appropriate identifier.
7. Create a second segue from the table view's prototype cell. This segue will be used to view existing entries. Give it an appropriate identifier as well.
8. Create a Cocoa Touch subclass of UITableViewController called EntriesTableViewController. Set this table view controller scene's class to it.
9. This prototype cell will be a custom cell. Add three labels. One for the entry's title, timestamp, and body text.
10. Create a Cocoa Touch subclass of UITableViewCell called EntryTableViewCell. Set this cell's class to it.
11. Create outlets for the three labels in the EntryTableViewCell class.

EntryDetailViewController

1. In the UIViewController scene, add a UITextField. Set its placeholder text to "Enter a title:"
2. Add a UITextView. Remove the Lorem Ipsum text from it. Constrain the text field right below the navigation bar, and the text view below that.
3. Add a navigation item to the view controller, then add a bar button item on the right side of the navigation bar. Change its "System Item" to "Save".
4. Create a Cocoa Touch subclass of UIViewController called EntryDetailViewController. Set this scene's class to the newly created subclass in the Identity Inspector.
5. Create an outlet from the text field and one from the text view. Also, create an action from the bar button item.

Part 2 - Entry and EntryController Setup

CoreDataStack

Create a swift file for your core data stack. Feel free to take the core data stack you used in this morning's project and paste it in this file. You may need to change the name of the persistent container to match the name of your data model file.

Entry

You will be using a model object called Entry.

1. Create a new Data Model file under the Core Data section. Make the name of the file match the name of your project.

2. Create a new entity and call it Entry. Keep the codegen as "Class Definition".

3. Add the following attributes to the Entry entity:

   • A title string.
   • A bodyText string.
   • A timestamp Date.
   • An identifier string.

4. Create a new swift file called "Entry+Convenience.swift".

5. Import CoreData in this file.

6. Add an extension on Entry.

7. Create a convenience initializer that takes in values for each of the Entry entity's attributes, and an instance of NSManagedObjectContext. Consider giving default values to the timestamp and identifier parameters in this initializer. This initializer should:

   • Call the Entry class' initializer that takes in an NSManagedObjectContext
   • Set the value of attributes you defined in the data model using the parameters of the initializer.

EntryController

1. Create a Swift file called "EntryController.swift". Make a class called EntryController.
2. Create a function called saveToPersistentStore(). This method should save your core data stack's mainContext. Remember that this will bundle the changes in the context, pass them to the persistent store coordinator who will then put those changes in the persistent store.
3. Create a function called loadFromPersistentStore() -> [Entry]. This method should:
   • Create an NSFetchRequest for Entry objects
   • Perform that fetch request on the core data stack's mainContext using a do-try-catch block.
   • Return the results of the fetch request.
   • In the catch statement, handle any errors and return an empty array.
4. Create an entries: [Entry] computed property. Inside of the computed property, call loadFromPersistentStore(). This will allow any changes to the persistent store become immediately visible to the user when accessing this array (i.e. in the table view showing a list of entries).
5. Create a "Create" CRUD method that will:
   • Initialize an Entry object
   • Save it to the persistent store.
   • NOTE: if Xcode is giving you a warning that the Entry object isn't being used, you can make the constant's name _, or add the @discarableResult attribute to the Entry's convenience intializer in the extension you created.
6. Create an "Update" CRUD method. The method should:
   • Have title and bodyText parameters as well as the Entry you want to update.
   • Change the title and bodyText of the Entry to the new values passed in as parameters to the function.
   • Update the entry's timestamp to the current time as well.
   • Save these changes to the persistent store.
7. Create a "Delete" CRUD method. This method should:
   • Take an an Entry object to delete
   • Delete the Entry from the core data stack's mainContext
   • Save this deletion to the persistent store.

Part 3 - View and View Controller Implementation

In the EntryTableViewCell class:

1. Add an entry: Entry? variable.
2. Create an updateViews() function that takes the values from the entry variable and places them in the outlets.
3. Add a didSet property observer to the entry variable. Call updateViews() in it.

In the EntryDetailViewController:

1. Add an entry: Entry? variable.
2. Add an entryController: EntryController? variable.

In the EntryTableViewController:

1. Add an entryController constant whose value is a new instance of EntryController.
2. Implement the numberOfRows method. It should return the amount of entries in the entryController.
3. Implement the cellForRowAt method. Remember to cast the call as EntryTableViewCell, then pass an Entry to the cell's entry property in order for it to call the updateViews() method to fill in the information for the cell's labels.
4. Add the viewWillAppear method. It should reload the table view.
5. Implement the commit editingStyle UITableViewDataSource method to allow the user to swipe to delete entries. You don't have to handle the editingStyle being .insert, just .delete.
6. Implement the prepare(for segue: ...) method. If the segue's identifier shows that the user is trying to create an entry, you will only need to pass the entryController to the destination view controller. If the identifier shows that they want to view an entry (by tapping a cell), pass the entryController and also the Entry that corresponds with the cell they tapped.

Back in the EntryDetailViewController:

1. Add an updateViews() method. Inside of it:
   • Make sure the view is loaded.
   • Set the view controller's title to the title of the entry if one was passed to this view controller, or "Create Entry" if not.
   • This method should also fill in the text field and text view's text to the title and bodyText of the entry respectively.
2. Add a didSet to the entry variable, and call updateViews() in it. Also call updateViews() in the viewDidLoad.
3. In the bar button item's action:
   • Unwrap the text from both the text field and text view.
   • Unwrap the entry property separately. If there is an entry, call the update method in the entryController. If not, call the createEntry method in the entryController instead. Either way, pop the view controller off the navigation stack.

Go Further

This project will be added on to as the Sprint progresses. As such, there are no "Go Further" challenges. However it is always a good idea to rebuild this project again. The more you build a project, the more you will learn from it. If you want to challenge yourself, try to write as much as you can without referencing these instructions.