This document provides an overview of lessons for building an iOS app, including a lesson on data modeling. It describes how to create a storyboard to visually represent the user interface with scenes and views. It explains how view controllers manage views and navigation between screens. It also shows code for creating, editing, displaying and deleting notes data using a data model to manage the data and share it between view controllers.

1. LOGIC & INTERFACE
Building our App

2. OVERVIEW
• Lesson 1: Introductions
• Lesson 2: iOS specifics
• Lesson 3: Data Model
• Lesson 4: Logic (Controller) & Interface

3. LESSON 3: DATA MODEL
• Hour 1: Storyboard
• Hour 2: Creating & Editing
• Hour 3: Display & Deleting Notes

4. Storyboard

5. Storyboard

6. Storyboard
• Visual representation of iOS user interface (UI)
• Shows screens of content and connections
between screens. Screens referred to as
“Scene”
• 1 “Scene” represents 1 View Controller and
Views
• Many “views” can be placed on 1 “scene” (e.g.
buttons, table views, text views). Think of views

7. Storyboard
• Each scene has a dock (displays icons
representing the top-level objects of the
scene)

8. Storyboard
• The “dock” is where we make connections
between code in our View Controller and its
Views (“visual objects on the scene”)

9. View Controllers
• A storyboard displays View Controllers and
corresponding Views visually

10. View Controllers
• A storyboard displays View Controllers and
corresponding Views visually

11. - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
// Override point for customization after application launch.
if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPad) {
UISplitViewController *splitViewController = (UISplitViewController *)self.window.rootViewController;
UINavigationController *navigationController = [splitViewController.viewControllers lastObject];
splitViewController.delegate = (id)navigationController.topViewController;
}
return YES;
}
View Controllers

12. View Controllers

13. View Controllers
UISplitViewController *splitViewController = (UISplitViewController *)self.window.rootViewController;

14. View Controllers
UINavigationController
• Sub-class of UIViewController
• a special View Controller that manages the navigation of
hierarchical content

15. View Controllers
UINavigationController
• It is a “container” that embeds content of other View
Controllers inside itself

16. Creating and Editing

17. View Controllers
AppDelegate.m
#import "AppDelegate.h"
#import "Data.h"
@implementation AppDelegate
- (BOOL)application:(UIApplication *)application
didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
[Data getAllNotes];
return YES;
}

18. View Controllers
MasterViewController.m
#import “Data.h"
- (void)insertNewObject:(id)sender
{
if (!_objects) {
_objects = [[NSMutableArray alloc] init];
}
//[_objects insertObject:[NSDate date] atIndex:0];
NSString *key = [[NSDate date] description];
[Data setNote:kDefaultText forKey:key];
[Data setCurrentKey:key];
[_objects insertObject:key atIndex:0];
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:0 inSection:0];
[self.tableView insertRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationAutomatic];
}

19. View Controllers
DetailViewController.m
#import “Data.h"
- (void)setDetailItem:(id)newDetailItem
{
if (_detailItem != newDetailItem) {
_detailItem = newDetailItem;
[Data setCurrentKey:_detailItem];
// Update the view.
[self configureView];
}
if (self.masterPopoverController != nil) {
[self.masterPopoverController dismissPopoverAnimated:YES];
}
}

20. View Controllers
DetailViewController.m
- (void)configureView
{
NSString *currentNote = [[Data getAllNotes] objectForKey:[Data getCurrentKey]];
if (![currentNote isEqualToString:kDefaultText]) {
self.tView.text = currentNote;
} else {
self.tView.text = @"";
}
[self.tView becomeFirstResponder];
}

21. View Controllers
DetailViewController.m
- (void)viewWillDisappear:(BOOL)animated
{
if (![self.tView.text isEqualToString:@""]) {
[Data setNoteForCurrentKey:self.tView.text];
} else {
[Data removeNoteForKey:[Data getCurrentKey]];
}
[Data saveNotes];
}

22. Displaying & Deleting

23. View Controllers
MasterViewController.m
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath
*)indexPath
{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"Cell"
forIndexPath:indexPath];
NSDate *object = _objects[indexPath.row];
cell.textLabel.text = [[Data getAllNotes] objectForKey:[object description]];
return cell;
}

24. View Controllers
MasterViewController.m
- (void)makeObjects
{
_objects = [NSMutableArray arrayWithArray:[[Data getAllNotes] allKeys]];
[_objects sortUsingComparator:^NSComparisonResult(id obj1, id obj2) {
return [(NSDate *)obj2 compare:(NSDate *)obj1];
}];
}

25. View Controllers
MasterViewController.m
- (void)insertNewObject:(id)sender
{
[self makeObjects];
if (!_objects) {
_objects = [[NSMutableArray alloc] init];
}
//[_objects insertObject:[NSDate date] atIndex:0];
NSString *key = [[NSDate date] description];
[Data setNote:kDefaultText forKey:key];
[Data setCurrentKey:key];
[_objects insertObject:key atIndex:0];
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:0 inSection:0];
[self.tableView insertRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationAutomatic];
[self performSegueWithIdentifier:kDetailView sender:self];
}

26. View Controllers
MasterViewController.m

27. View Controllers
MasterViewController.m
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPad) {
NSDate *object = _objects[indexPath.row];
self.detailViewController.detailItem = object;
}
}
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([[segue identifier] isEqualToString:@"showDetail"]) {
NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];
NSDate *object = _objects[indexPath.row];
[[segue destinationViewController] setDetailItem:object];
}
}

28. View Controllers
MasterViewController.m
- (void)viewWillAppear:(BOOL)animated
{
[super viewDidAppear:animated];
[self makeObjects];
[self.tableView reloadData];
}

29. View Controllers
MasterViewController.m
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle
forRowAtIndexPath:(NSIndexPath *)indexPath
{
if (editingStyle == UITableViewCellEditingStyleDelete) {
[Data removeNoteForKey:[_objects objectAtIndex:indexPath.row]];
[Data saveNotes];
[_objects removeObjectAtIndex:indexPath.row];
[tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];
} else if (editingStyle == UITableViewCellEditingStyleInsert) {
// Create a new instance of the appropriate class, insert it into the array, and add a new row to the table
view.
}
}

30. OVERVIEW
• Lesson 1: Introductions
• Lesson 2: iOS specifics
• Lesson 3: Data Model
• Lesson 4: Logic (Controller) & Interface