Scott Leberknight

iOS

The Big Picture

Patterns

Languages

APIs

Tools

Patterns

MVC(S)

Notifications

Delegation

Protocols

Target-Action

Languages

Objective-C

C(lower-level APIs)

APIsCore

Lots more...

Core GraphicsFoundationUIKit

MapKit

GameKit

Core Location

Core Data Accounts

OpenGL

Social...

XCodeTools

Tools Interface Builder

First App*

MVC

Target-Action

Delegation

http://github.com/sleberknight/fortune-ios-app*

Model

@property (nonatomic, copy) NSArray *fortunes;

FOViewController.h

View

FOViewController.xib

Outlets

Actions

&

Outlets

in XCode...

FOViewController.h

Outlets in IB...

FOViewController.xib

Target-Action

Action - “touch up inside” Target - File’s Owner(our view controller)

Controller

FOViewController.h

#import <UIKit/UIKit.h>

@interface FOViewController : UIViewController

// Model@property (nonatomic, copy) NSArray *fortunes;

// Outlets@property (nonatomic, strong) IBOutlet UITextView *fortuneField;

// Actions- (IBAction)showFortune:(id)sender;

@end

(IBOutlet & IBAction keywords allow

connections in Interface Builder)

Controller

FOViewController.m

#import "FOViewController.h"

@implementation FOViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil { self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];

if (self) { _fortunes = @[ @"A dubious friend may be an enemy in camouflage.", @"A feather in the hand is better than a bird in the air.", @"A friend asks only for your time not your money.", // ... ]; } return self;}

- (IBAction)showFortune:(id)sender { int fortuneIndex = arc4random() % [_fortunes count]; NSLog(@"fortuneIndex: %d", fortuneIndex); NSString *fortune = [_fortunes objectAtIndex:fortuneIndex]; [_fortuneField setText:fortune];}

@end

#import <UIKit/UIKit.h>

// Inherits from UIResponder// Conforms to UIApplicationDelegate protocol

@interface FOAppDelegate : UIResponder <UIApplicationDelegate>

@property (strong, nonatomic) UIWindow *window;

@end

Delegation

FOAppDelegate.h

#import "FOAppDelegate.h"#import "FOViewController.h"

@implementation FOAppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions{ self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];

// Create our view controller; set it as the root view controller FOViewController *viewController = [[FOViewController alloc] initWithNibName:@"FOViewController" bundle:nil]; [[self window] setRootViewController:viewController];

self.window.backgroundColor = [UIColor whiteColor]; [self.window makeKeyAndVisible]; return YES;}

@end

Delegation

FOAppDelegate.m

Run It!

2. Tap “Get Fortune!”

1. Load view controllerin App Delegate

3. showFortune: called

4. Get fortune from model

5. Call setText: on UITextView

Objective-C

Object-oriented(layered on top of C)

Message sending

Single-inheritance

Protocols (like Java interfaces)

Objective-C (continued)

Properties

Selectors

Blocks (like closures)

ARC (automatic reference counting)

GCD (Grand Central Dispatch)

Properties

@property (nonatomic, strong) IBOutlet UITextView *fortuneField;

* Compiler generates:

- instance variable _fortuneField

- getter method fortuneField

- setter method setFortuneField

* IBOutlet indicates it can be an outlet to IB

* Modifiers determine threading and storage model

Sending Messages

[detailViewController setItem:newItem];

receiver

selector

argument

Sending Messages

[self presentViewController:navigationController animated:YES completion:nil];

receiver

selector arguments

Creating Objects

allocate memory

initialize object

WLItemsViewController *itemsViewController = [[WLItemsViewController alloc] init];

Blocks

int amountToAdd = 7;int (^adder)(int) = ^(int num) { return num + amountToAdd;};

NSLog(@"%d", adder(3));// prints "10" to XCode console

[detailViewController setDismissBlock:^{ [[self tableView] reloadData];}];

Blocks - inline

[self tableView] is capturedfrom scope defining block!

Objective-C really is an OK language,once you get used to its quirks,

and it keeps improving...

Core APIs

UIKit

Foundation

Core Graphics

UIKit

“The UIKit framework provides the classes needed to construct and manage an application’s user interface for iOS. It provides an application object, event handling, drawing model, windows, views, and controls specifically designed for a touch screen interface.”

http://developer.apple.com/library/ios/#documentation/uikit/reference/UIKit_Framework/_index.html

UIKit & Grand Central Dispatch

"For the most part, UIKit classes should be used only from an application’s main thread. This is particularly true for classes derived from UIResponder or that involve manipulating your application’s user interface in any way."

http://developer.apple.com/library/ios/#documentation/uikit/reference/UIKit_Framework/Introduction/Introduction.html#//apple_ref/doc/uid/TP40006955-CH1-SW1

-(void)handleIncoming:(NSData *)data{ dispatch_async(dispatch_get_main_queue(), ^{

// Retrieve data...

// Update the UI using UIKit methods...

});}

Update UI using GCD

Foundation

“The Foundation framework defines a base layer of Objective-C classes. In addition to providing a set of useful primitive object classes, it introduces several paradigms that define functionality not covered by the Objective-C language.”

http://developer.apple.com/library/mac/#documentation/cocoa/reference/foundation/ObjC_classic/_index.html

Core Graphics

“The Core Graphics framework is a C-based API that is based on the Quartz advanced drawing engine. It provides low-level, lightweight 2D rendering with unmatched output fidelity. You use this framework to handle path-based drawing, transformations, color management, offscreen rendering, patterns, gradients and shadings, image data management, image creation, masking, and PDF document creation, display, and parsing.”

http://developer.apple.com/library/ios/#documentation/coregraphics/reference/coregraphics_framework/_index.html

Many, Many More APIs

Core Location MapKit

Quartz Core Animation

AdSupport...Core Motion

Sample Application - Wishlist*

http://github.com/sleberknight/wishlist-ios-app

Displays list of items

Detail view to create/edit items

Move and delete items in list

Choose images for items

*

List of items Editing list

Add/edititem

Chooseimage

Patterns

MVC(S):

Model, View, Controller (, Store)

“Store” is like a DAO (data access object)

Extract store logic from controllers

Patterns

Inheritance - e.g. table view controller

Delegation - e.g. image picker delegate

Notification - e.g. low-memory warning

Model -

#import <Foundation/Foundation.h>

@interface WLItem : NSObject <NSCoding>

-(id)initWithItemName:(NSString *)name;

-(id)initWithItemName:(NSString *)name occasion:(NSString *)occasion store:(NSString *)store price:(int)price;

@property (nonatomic, strong) WLItem *containedItem;@property (nonatomic, weak) WLItem *container;

@property (nonatomic, copy) NSString *itemName;@property (nonatomic, copy) NSString *occasion;@property (nonatomic, copy) NSString *store;@property (nonatomic, assign) int price;@property (nonatomic, copy) NSString *imageKey;@property (readonly, nonatomic, copy) NSDate *dateCreated;@property (nonatomic, copy) NSDate *dateModified;

@end

WLItem

Views

UITableView (presents list of items)

* App delegate creates table view controller programmatically within a navigation controller

* Not defined in XIB

* Edit and + buttons defined in code

Views Detail View Controller

ControllersWLItemsViewController:

Subclass of:

Conforms to: UITableViewDelegateUITableViewDataSource

UITableViewController

Uses UINavigationController to present detail view controller for adding/editing items

Manages moving/deleting items

Responsible for creating table view cells

ControllersWLDetailViewController:

Subclass of:

Conforms to: UITextFieldDelegate

UINavigationControllerDelegate

UIViewController

UIImagePickerControllerDelegate

UIPopoverControllerDelegate

Responsible for loading/saving items & images

Manages image picking controllers

Manages text changed notifications

Stores

WLItemStore

WLImageStore

Stores WLItem objects

Stores UIImage objects

Application Flow

WLAppDelegateapplication:didFinishLaunchingWithOptions

- Create a WLItemsViewController

- Embed WLItemsViewController in UINavigationController

Tap + button, fires addNewItem: which presents detail view controller

- Create a UINavigationController

List editing UI is automatic when add button using editBarButton

WLItemsViewController viewWillAppear: loads table view

viewWillAppear:animated:

viewDidLoad: sets background color

WLDetailViewController init: creates Cancel & Done bar button items

- Sets up form for editing/adding item

- Display image if present

- Register for text change notifications

viewWillDisappear: saves item data

done: dismisses controller, completion handler reloads table data

Tapping camera button invokes takePicture:

UIImagePickerController presents camera or picture library

UIImagePickerController delegate (controller) handles selected image

imagePickerController:didFinishPickingMediaWithInfo retrieves selected image, stores it, and displays it

Use Core Graphics to add a border around image

Use Quartz to add a shadow around image

UITextFieldDelegate method textFieldShouldReturn: dismisses keyboard when return tapped

UIControlEventEditingChanged events trigger selector textChanged: which adds modified date when editing existing items

On iPad use a UIPopoverController for selecting images

UIPopoverController was used to select the delicious image...

One more thing...

Storyboards (an alternative way to define app flow)

Summary

Objective-C

Patterns, Languages, APIs, Tools

MVC(S), Delegation, Protocols

Lots of APIs to use (and learn)

XCode / Interface Builder (IB)

Connect outlets & actions in IB

References

http://www.bignerdranch.com/book/ios_programming_the_big_nerd_ranch_guide_rd_edition_

http://pragprog.com/book/adios/ios-sdk-development

Sample Code

http://github.com/sleberknight/fortune-ios-app

Fortunes:

http://github.com/sleberknight/wishlist-ios-app

Wishlist:

Fortunes:

My Info

scott.leberknight at nearinfinity.com

twitter.com/sleberknight

www.sleberknight.com/blog

www.nearinfinity.com/blogs/scott_leberknight/all/