Students will build a simple journal app to practice MVC separation, protocols, master-detail interfaces, table views, and persistence using CloudKit.

Journal is an excellent app to practice basic C.R.U.D functions using CloudKit

Students who complete this project independently are able to:

Part One - Model Objects and Controllers

• Create a custom model object with a memberwise initializer and an initializer that takes in a CKRecord
• In the initializer that takes in a CKRecord, use the key-value pairs from the CKRecord to create the entries properties as you would a dictionary
• Add property for the CKRecordID
• Add an extension on CKRecord that initializes an instance of CKRecord with your custom model object. Here is where you set the key-value pairs.
• Understand, create, and use a shared instance
• Create a model object controller with create, read, update, and delete functions

Part Two - User Interface

• Implement a master-detail interface
• Implement the UITableViewDataSource protocol
• Understand and implement the UITextFieldDelegate protocol to dismiss the keyboard
• Create relationship segues in Storyboards
• Understand, use, and implement the 'updateViews' pattern
• Implement 'prepare(for segue: UIStoryboardSegue, sender: Any?)' to configure destination view controllers

Part Three - Controller Implementation

• Add data persistence using CloudKit, managing CKRecords and Model Objects.
• Upon launch, fetch the CKRecords from the private database and turn those records into your model object.

Part One - Model Objects and Controllers Before you begin make sure you have enabled iCloud in your apps Cababilities settings, unchecked the "key-value storage" setting and checked "CloudKit" setting. It may take sometime for a new CKContainer to appear in the CloudKit dashboard so its important you complete this step first.

Entry

Create an Entry model class that will hold title, text, and ckRecordID properties for each entry.

1. Add a new Entry.swift file and define a new Entry class 3. Import CloudKit 3. Add properties for , title, body text and and ckRecordID of type CKRecordID or CKRecord.ID as of Swift 4.2 4. Add a memberwise initializer that takes parameters for each property. Give the CkRecordID you pass in a default parameter value of CKRecord.ID(recordName: UUID().uuidString)). *_This will allow you to refer back to entry objects CKRecord without an optional CKRecordID. 5. Add a failable convenience initializer that takes in only a CKRecord 6. Look up the documentation for CKRecord. Notice it acts as a dictionary. 7. Get the value from your properties keys. Typically the value will be the string version of your property names. Its a good idea to create a set of constants outside of your class to make sure these keys stay uniform.

struct Constants{
        static let titleKey = "Title"
        static let bodyKey = "Body"
    }

• You can then use these keys to pull values out of the CKRecord coming from your convenience initalizer.
• You will need to cast these properties as Strings as you unwrap them at the beginning of your conveniece initializer. See the example below for reference.

 guard let title = ckRecord[Constants.titleKey] as? String else {return nil}

Add an extension to CKRecord and then create a convenience initializer

1. In an Extension on CKRecord Create a convenience initializer that takes in an Entry as it's only parameter 2. Call the designated initializer of the CKRecord. The record type is going to be a string representation of your model object ("Entry"). Add this as a third static property to your Constants struct.

self.init(recordType: Constants.recordKey)

4. The record ID is going to be the ckRecordID property on the entry object your initializer takes in as a parameter 5. This is where you set the key-value pairs for the CKRecord 6. After the designated initializer, you can call self.setValue(value: forKey:) (The key is going to be a string representation of your property from your Constants struct, the value is going to be the entry parameter's value). For example:

self.setValue(entry.title, forKey: Constants.titleKey)

EntryController

Create a model object controller called EntryController that will manage adding, reading, updating, and removing entries. We will follow the shared instance design pattern because we want one consistent source of truth for our entry objects that are held on the controller.

1. Add a new EntryController.swift file and define a new EntryController class inside. 2. Add an entries array property, and set its value to an empty array

Save

1. Create a save(entry: ...) function that takes in an entry, and completion: @escaping (Bool) -> () that will take in an entry, and save it to the private database 2. Turn your entry into a CKRecord (Using the convenience initializer we used on CKRecord) 3. Access your private database using the CKContainer and then call the save method

CKContainer.default().privateCloudDatabase.save(record: CKRecord, completionHandler:(CKRecord?, Error?) -> Void)

4. Handle the error that this function may complete with and pass false into the completion. If you successfully saved your record, unwrap it and call the convenience initalizer to create an entry from the record. Append this newly initalized entry to your entries array. Finally, call completion and pass in true. *This process of initalizing another entry from our record may seem redundant, but it ensures the data in CloudKit will match what the user sees locally (i.e. if the record fails to save for some reason, it will not show up on the users phone).

Create

1. Create a addEntryWith(title: ...) function that takes in a title, and body, and completion: @escaping (Bool) -> Void creates a new instance of Entry, and adds it to the entries array 2. Using the title and text properties, create a new Entry with it's memberwise initializers. 3. With the Entry you just created, call your save(entry:completion:) method created earlier 4. In the completion handler of the the save(entry:completion:), if you were able to successfully save it to CloudKit, call completion(true). If not, call completion(false)

Fetch

1. Create a fetchEntries(completion: @escaping (Bool)->()) function that only has a completion handler. This will fetch all the entries in your private database. 2. In order to perform a query to the private databse, you will need to create a CKQuery. 3. A CKQuery takes in two parameters, recordType: String and predicate: NSPredicate The recordType will be a the string representation of our CKRecord. You can call this string off of the static property in your Constants struct. 4. NSPredicate is a definition of logical conditions (true false) used to constrain a search either for a fetch or for in-memory filtering. For this project we want to get all entries back from the private database, so we will be using the initializer that takes in a value, and we will be setting that value to true This tells the predicate to just return everything. 5. Now call CKContainer.default().privateCloudDatabase.perform(query: inZoneWith: completionHandler:). Plug in your CKQuery for the query, and nil for inZoneWith. In smaller apps you typically will keep this value nil. 6. The completionHandler gives us an optional error and an optional array of CKRecordss. Check for error, and if there is an error, call completion(false) and return 7. Unwrap your array of records, and if it's nil. call completion(false) and return 8. Now that you have an array of CKRecords, you can loop through the array and attempt to initialize an Entry with them. We are able to do this because we created a the failable initializer in the Model that takes in a CKRecord

• You might want to create an empty Entry array above the loop that you can append the entries to. 9. After the loop, you can set self.entries to equal your array you created. Call completion(true)

Black Diamonds

*Implement the Equatable protocol for the Entry class *Write a function which allows you to delete entries locally and in CloudKit. You will need to call the delete method on your private database. *Write a function which allows you to modify entries in locally and in Cloudkit. Hint: You will need to use the CKModifiyRecordsOperation class. Documenation Second Hint: This might be on your test

Part Two - User Interface

Master List View

Build a view that lists all journal entries. You will use a UITableViewController and implement the UITableViewDataSource functions.

You will want this view to reload the table view each time it appears in order to display newly created entries.

1. Add a UITableViewController as your root view controller in Main.storyboard and embed it into a UINavigationController 2. Create an EntryListTableViewController file as a subclass of UITableViewController and set the class of your root view controller scene 3. Implement the UITableViewDataSource functions using the EntryController entries array

• Pay attention to your reuseIdentifier in the Storyboard scene and your dequeueReusableCell(withIdentifier:for:) function call 4. Set up your cells to display the title of the entry 5. Add a UIBarButtonItem to the UINavigationBar with the plus symbol
• Select 'Add' in the System Item menu from the Identity Inspector to set the button as a plus symbol, these are system bar button items, and include localization and other benefits

6. Call the fetchEntries function from your EntryController in the ViewDidLoad of the tableview controller. In the completion block for fetchEntries call self.tableView.reloadData()

Detail View

Build a view that provides editing and view functionality for a single entry. You will use a UITextField to capture the title, a UITextView to capture the body, a UIBarButtonItem to save the new or updated entry, and a UIButton to clear the title and body text areas.

Your Detail View should follow the 'updateViews' pattern for updating the view elements with the details of a model object. To follow this pattern, the developer adds an 'updateViews' function that checks for a model object. The function updates the view with details from the model object.

1. Add an EntryDetailViewController file as a subclass of UIViewController and an optional entry property to the class 2. Add a UIViewController scene to Main.storyboard and set the class to EntryDetailViewController 3. Add a UITextField for the entry's title text to the top of the scene, add an outlet to the class file called titleTextField, and set the delegate relationship (To set the delegate relationship control drag from the UITextField to the current view controller in the scene dock or call myTextField.delegate = self in the view controller ViewDidLoad functions) 4. Implement the delegate function textFieldShouldReturn to resign first responder to dismiss the keyboard (*Before you implement the delegate function be sure to adopt the UITextFieldDelegate protocol*) 5. Add a UITextView for the entry's body text beneath the title text field and add an outlet to the class file bodyTextView. 6. Add a UIButton beneath the body text view and add an IBAction to the class file that clears the text in the titleTextField and bodyTextView. 7. Add a UIBarButtonItem to the UINavigationBar as a Save System Item and add an IBAction to the class file called saveButtonTapped (*You may need to add a segue from EntryListTableViewController to see a UINavigationBar on the detail view, and a UINavigationItem to add the UIBarButtonItem to the UINavigationBar, this will be covered in the next section*) 9. Add an updateViews() function that checks if the optional entry property holds an entry. If it does, implement the function to update all view elements that reflect details about the model object entry (in this case, the titleTextField and bodyTextView) 10. Update the viewDidLoad() function to call updateViews()

Segue

You will add two separate segues from the List View to the Detail View. The segue from the plus button will tell the EntryDetailViewController that it should create a new entry. The segue from a selected cell will tell the EntryDetailViewController that it should display a previously created entry, and save any changes to the same.

1. Add a 'show' segue from the Add button to the EntryDetailViewController scene and give the segue an identifier (*When naming the identifier, consider that this segue will be used to add an entry*) 2. Add a 'show' segue from the table view cell to the EntryDetailViewController scene and give the segue an identifier (*When naming the identifier, consider that this segue will be used to edit an entry*) 3. Add a prepare(for segue: UIStoryboardSegue, sender: Any?) function to the EntryListTableViewController 4. Implement the prepare(for segue: UIStoryboardSegue, sender: Any?) function. If the identifier is 'toShowEntry' we will pass the selected entry to the DetailViewController, which will call our updateViews() function

• You will need to capture the selected entry by using the indexPath of the selected cell
• Remember that the updateViews() function will update the destination view controller with the entry details
• Since we aren't passing an entry if the identifier is 'toAddEntry' we don't need to account for this in our prepare(for segue: UIStoryboardSegue, sender: Any?)

Black Diamonds

• Add swipe to delete functionality which removes entries locally and from CloudKit.
• In the detail view controller, when the save button is tapped, check to see if an entry exists. If it does, update the entry locally and in CloudKit. If it does not, create a new entry
• Add a CKSubscription that sends an alert when an entry is added

Your app should now function properly. Run the app and test for bugs.