This document summarizes the steps to build a simple iOS game called KillTime using the Cocos2D game framework. It discusses setting up the project, adding a background, player character and enemy targets, detecting touches to shoot bullets, checking for collisions, animating sprites, and tracking the body count with labels and sound effects. The document provides code snippets to implement the game's core functionality and gameplay using Cocos2D concepts like scenes, layers, sprites, actions and the touch handling API.

1. iOS Game Development
with Cocos2D
SaalisUmer
saalis.umer@vinsol.com

2. iOS Game Development
with Cocos2D
Part 1: Why Cocos2D?
Part 2: Cocos2D Basics
Part 3: Let’s build a Cocos2D game

3. Part 1:
Why Cocos2D?

4. Anatomy of a simple game
CPU & GPU

5. Meet Cocos2D for iPhone
Open source iOS game development framework
Developed by Ricardo Quesada, acqui-hired by
Zynga (2011)
Stable v1.1 Based on OpenGL ES 1.1
Beta v2.0 Based on OpenGL ES 2.0
3,500+ iOS games shipped

6. The Cocos2D Family
Cocos3D
(Obj-C)
Cocos2d-Android
(Java)
Cocos2d-Mac
Cocos2d-X (Obj-C)
iPhone/Android (C++)
Cocos2d-XNA Cocos2d-HTML5
Windows Phone 7 (C#) Web (Javascript)

7. Proven Success

8. Great Effort-Flexibility Balance
Direct OpenGL/
100 CoreGraphics
Cocos2D/Sparrow
Unity/Corona
0
Flexibility

9. Cross Device, Cross Resolution

10. Active Ecosystem

11. And most importantly..
Tons of great features for games
Sprite Sheets Scene Transitions Parallax Scrolling
Effects: Actions:
Tile Map Support
Lense, Ripple, Wave.. Move, Rotate, Scale..
Particle Systems Integrated Physics Engines Text Rendering
Ribbons Shaders (v2.0) Sound Support

12. Part 2:
Cocos2D Basics

13. Basic Cocos2D Concepts
Class that creates and handle the main Window
Director and manages how and when to execute the Scenes.

14. Basic Cocos2D Concepts
Creates and handle the main Window
Director and manages how and when to execute the Scenes.
A scene (implemented with the CCScene object) is more
Scenes or less an independent piece of the app workflow. .

15. Basic Cocos2D Concepts
Creates and handle the main Window
Director and manages how and when to execute the Scenes.
A scene (implemented with the CCScene object) is more
Scenes or less an independent piece of the app workflow. .
A CCLayer has a size of the whole drawable Layers
area, and knows how to draw itself.

16. Basic Cocos2D Concepts
Creates and handle the main Window
Director and manages how and when to execute the Scenes.
A scene (implemented with the CCScene object) is more
Scenes or less an independent piece of the app workflow. .
A layer has a size of the whole drawable
Layers
area, and knows how to draw itself.
It is a 2D image that can be moved, Sprites
rotated, scaled, animated, etc.

17. Director & Scenes
Director Loss
Intro Main Menu Level I Level 2 Victory
Options
High Scores
Game made up of “game screens” called Scenes
Each Scene can be considered a separate app
Director handles main window and executes Scenes

18. Layers
Each Scene contains several full screen Layers
Layers contain Sprites which are the game elements
Layers useful for Controls, Background, Labels, Menus.

19. Nodes
Nodes are anything that gets drawn or contains
things that get drawn (= Scene, Layer, Sprite)
Can: Contain other Nodes
Schedule periodic callbacks
Execute Actions

20. Sprites in Action
Create
CCSpriteFrame* spriteFrame = [[CCSpriteFrameCachesharedSpriteFrameCache]
spriteFrameByName:@"sprite.png”];
CCSprite* sprite = [CCSpritespriteWithSpriteFrame:spriteFrame];

21. Sprites in Action
winSize.height
Add to Layer
(x,y) at anchor point
winSize.width
(0,0)
sprite.position = ccp(x, y);
[layer addChild:sprite z:5 tag:666];

22. Sprites in Action
Move
CCMoveTo *moveToAction = [CCMoveToactionWithDuration:duration
position:newPosition];
[sprite runAction:moveToAction];
Properties can be transformed directly or through actions

23. Sprites in Action
Scale/Rotate
CCScaleTo *scaleToAction = [CCScaleToactionWithDuration:durationscale:scale];
CCRotateBy *rotateByAction = [CCRotateByactionWithDuration:durationangle:angle];
CCSequence *sequence = [CCSequenceactions:scaleToAction, rotateByAction, nil];
[sprite runAction:sequence];

24. Sprites in Action
Animate
CCAnimation* animation = [[CCAnimationCachesharedAnimationCache]
animationByName:@"animation"];
CCAnimate* animateAction = [CCAnimateactionWithAnimation:animation];
[sprite runAction:animateAction];

25. Sprites in Action
Schedule Updates
[scene schedule:@selector(updateSprite:) interval:interval];

26. Actions
Can be performed on Sprites or any Node
Basic Move, Scale, Rotate, Bezier, Hide, Fade, Tint..
Composition Sequence, Repeat, Spawn, RepeatForever..
Ease Ease, EaseExponential, EaseBounce..
Effects Lens, Liquid, Ripple, Shaky, Twirl, Waves..
Special CallFunc, Follow..

27. Spritesheets
Added as a child to the layer
Created with TexturePacker or Zwoptex
Memory considerations, 16bit images, .pvr.ccz

28. Controls
- (void)ccTouchesBegan:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)ccTouchesMoved:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)ccTouchesEnded:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)ccTouchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event;
Implement directly based on CCStandardTouchDelegate
Can use UIGestureRecognizer classes
Open source implementations of joypad/buttons available

29. Part 3:
Let’s Make a Game!

30. Part 3:
Let’s Make a Game!
..but first we need a story, graphics, music and sfx :)

31. KillTime
Because he likes to kill paratroopers

32. Graphics
http://www.freewebs.com/teh_pro/sprites.htm

33. Music & SFX
Background music, shoot sound, death sound

34. Steps for making KillTime
Application Setup
Step 1: Adding Background
Step 2: Adding Our Hero
Step 3: Adding Bad Guys (Game Logic)
Step 4: Killing Bad Guys (Adding UI)
Step 5: Check for Bad Guy Death
Step 6: Animating Our Hero
Step 7: Animating Bad Guys Dying
Step 8: Adding Body Count
Step 9: Adding Sound & Music

35. New Cocos2D Project

36. HelloWorldScene.h
@interface HelloWorldLayer : CCLayer
{
// Player sprite
CCSprite *_player;
// Target and bullet sprite arrays
NSMutableArray *_targets;
NSMutableArray *_bullets;
! // Body count counter and isShooting flag
int _bodyCount;
BOOL _isShooting;
!
// For body count label
CCLabelTTF *_labelTitle;
CCLabelTTF *_labelCount;
}

37. HelloWorldScene.m
// Create the new scene including this layer
+(id) scene
{
! // Create the scene
CCScene *scene = [CCScene node];
!
! // Create the layer
HelloWorldLayer *layer = [HelloWorldLayer node];
!
! // add layer as a child to scene
! [scene addChild: layer];
!
! // return the scene
return scene;
}

38. Hello World

39. Step 1: Adding Background
(In init)
// Get the window size to place elements
CGSizewinSize = [[CCDirectorsharedDirector] winSize];
// Add the background image
CCSprite *background = [CCSpritespriteWithFile:@"background.png"];
background.position = ccp(winSize.width/2, winSize.height/2);
[self addChild:background z:0];
self.isTouchEnabled = YES; _bullets = [[NSMutableArrayalloc]init];
_targets = [[NSMutableArrayalloc]init];

40. Step 1: Adding Background

41. Step 2: Adding Our Hero
Preload the spritesheet
(In init)
// Load the sprite sheet
CCSpriteBatchNode *batchNode = [CCSpriteBatchNode
batchNodeWithFile:@”spritesheet.pvr.ccz"];
[self addChild:batchNode];
// Load the sprites into the shareSpriteFrameCache
[[CCSpriteFrameCachesharedSpriteFrameCache]
addSpriteFramesWithFile:@”spritesheet.plist"];

42. Step 2: Adding Our Hero
Add the hero sprite
// Add the player sprite
CCSpriteFrame* playerFrame = [[CCSpriteFrameCachesharedSpriteFrameCache]
spriteFrameByName:@"player1.png"];
_player = [CCSpritespriteWithSpriteFrame:playerFrame];
_player.position = ccp(_player.contentSize.width/2 + 10, winSize.height/2);
[self addChild:_player z:1];

43. Step 2: Adding Our Hero

44. Step 3: Adding Bad Guys (Game Logic)
Schedule a new target every second
(in init)
[self schedule:@selector(addTarget:) interval:1.0f];

45. Step 3: Adding Bad Guys (Game Logic)
Create a sprite for the target
// Create a new enemy
-(void)addTarget:(ccTime)dt {
// Create the target sprite
CCSpriteFrame *targetFrame = [[CCSpriteFrameCachesharedSpriteFrameCache]
spriteFrameByName:@"target.png”];
CCSprite *target = [CCSpritespriteWithSpriteFrame:targetFrame];
// Add the target to the layer and the array
! [self addChild:target];
! [_targets addObject:target];}

46. Step 3: Adding Bad Guys (Game Logic)
Generate a random x position for the target
// Determine where to spawn the target along the X axis
CGSizewinSize = [[CCDirectorsharedDirector] winSize];
// Find a random X for the target in the right half of the screen
intminX = winSize.width/2;
intmaxX = winSize.width - target.contentSize.width;
intrangeX = maxX - minX;
intactualX = (arc4random() % rangeX) + minX;
target. position = ccp (actualX, 320 );
target.anchorPoint = ccp(0, 0);
// Determine speed of the target
intminDuration = 2.0;
intmaxDuration = 4.0;
intrangeDuration = maxDuration - minDuration;
intactualDuration = (arc4random() % rangeDuration) + minDuration;

47. Step 3: Adding Bad Guys (Game Logic)
Create a move action for the target with a
callback when reaching the bottom
// Create and run the actions
CCMoveTo* moveTarget = [CCMoveToactionWithDuration:actualDuration
Position:ccp(actualX,-target.contentSize.height/2)];
CCCallFuncN* actionForTargetMoveDidFinish = [CCCallFuncN
actionWithTarget:selfselector:@selector(targetMoveFinished:)];
[target runAction:[CCSequenceactions:moveTarget, actionForTargetMoveDidFinish, nil]];

48. Step 3: Adding Bad Guys (Game Logic)
Add the callback method for a target that
dies or reaches the bottom
// Method for removing a target that has died or reached the
bottom
-(void)targetMoveFinished:(id)sender {
CCSprite *target = (CCSprite *)sender;
[ self removeChild :target cleanup : YES ];
[_targets removeObject:target];
}

49. Step 3: Adding Bad Guys (Game Logic)

50. Step 4: Killing Bad Guys (Adding UI)
Detect the touch
- (void)ccTouchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
// Choose one of the touches to work with
UITouch *touch = [touches anyObject];
CGPoint location = [touch locationInView:[touch view]];
location = [[CCDirectorsharedDirector] convertToGL:location];
if (!_isShooting) {
_isShooting = YES;

51. Step 4: Killing Bad Guys (Adding UI)
Create the bullet
// Create the bullet
CCSpriteFrame* bulletFrame = [[CCSpriteFrameCachesharedSpriteFrameCache]
spriteFrameByName: @"bullet.png" ];
CCSprite* bulletSprite = [CCSpritespriteWithSpriteFrame:bulletFrame];
bulletSprite.position = _player.position;
// Bullet actions
CCCallFuncN* actionForRemoveBullet = [CCCallFuncNactionWithTarget:self
selector:@selector(removeBullet:)];
CCMoveBy* bulletMoveBy = [CCMoveBy actionWithDuration:1.0f
position:ccp(winSize.width, 0)];
[bulletSpriterunAction:[CCSequenceactionOne:bulletMoveBy
two:actionForRemoveBullet]];
// Add bullet to layer and array
[self addChild:bulletSprite];
[_bullets addObject:bulletSprite];
_isShooting = NO;

52. Step 4: Killing Bad Guys (Adding UI)

53. Step 5: Check for Bad Guy Death
-(void)update:(ccTime)dt {
CCSprite* bulletToRemove = nil;
for (CCSprite *bullet in _bullets) {
for (CCSprite* target in _targets) {
CGRecttargetBox = CGRectMake(target.position.x, target.position.y,
[target boundingBox].size.width, [target boundingBox].size.height);
// Check if bullet is in the target's bounding box
if (CGRectContainsPoint(targetBox, bullet.position)) {
// Animate target death and remove target
bulletToRemove = bullet;
}
}
}
// Remove bullet if target was hit
if (bulletToRemove != nil) {
[self removeChild:bulletToRemovecleanup:YES];
[ _bullets removeObject :bulletToRemove];
}
}

54. Step 5: Check for Bad Guy Death

55. Step 6: Animating Our Hero
Preload the animation from the spritesheet
Adding Player animation in init
(In init)
// Load the animation for player
NSMutableArray *animFrames1 = [NSMutableArray array];
for (inti = 1; i< 11; i++) {
CCSpriteFrame *frame = [[CCSpriteFrameCachesharedSpriteFrameCache] spriteFrameByName:
[NSStringstringWithFormat:@"player%d.png”,i]];
[animFrames1 addObject:frame];
}
[[CCAnimationCachesharedAnimationCache] addAnimation:[CCAnimation
animationWithFrames:animFrames1 delay:FRAME_DELAY] name:@"player"];!

56. Step 6: Animating Our Hero
Preload the animation from the spritesheet
Adding Kill animation in init
(In init)
//// Load the animation for villain kill
NSMutableArray *animFrames2 = [NSMutableArray array];
for (inti = 1; i< 8; i++) {
CCSpriteFrame *frame2 = [[CCSpriteFrameCachesharedSpriteFrameCache] spriteFrameByName:
[NSStringstringWithFormat:@"kill%d.png",i]];
[animFrames2 addObject:frame2];
}
[[CCAnimationCachesharedAnimationCache] addAnimation:[CCAnimation
animationWithFrames:animFrames2 delay:FRAME_DELAY*5] name:@"kill"];

57. Step 6: Animating Our Hero
Animate the hero when shooting
(In ccTouchesEnded)
// Actions for shooting animation
CCCallFunc* actionForShootDidEnd = [CCCallFuncactionWithTarget:self
selector:@selector(shootDidEnd)];
CCAnimation* playerShootAnimation = [[CCAnimationCachesharedAnimationCache]
animationByName:@"player"];
CCAnimate* shootAnimate = [CCAnimateactionWithAnimation:playerShootAnimation];
[_player runAction:[CCSequenceactionOne:shootAnimatetwo:actionForShootDidEnd]];

58. Step 6: Animating Our Hero

59. Step 7: Animating Bad Guys Dying
(in update)
// Set up actions for animation and target removal
CCCallFuncN* actionForDeathDidFinish = [CCCallFuncNactionWithTarget:self
selector:@selector(targetMoveFinished:)];
CCAnimate* deathAnimation = [CCAnimateactionWithAnimation:[[CCAnimationCache
sharedAnimationCache] animationByName:@”kill"] restoreOriginalFrame:NO];
[target runAction:[CCSequenceactionOne:deathAnimationtwo:actionForDeathDidFinish]];

60. Step 7: Animating Bad Guys Dying

61. Step 8: Adding Body Count
(In init)
NSString* bodyCountString = [NSStringstringWithFormat:@"%d", _bodyCount];
_labelCount = [CCLabelTTFlabelWithString:bodyCountStringfontName:@"Arial"
fontSize : 16 ];
_labelCount.color = ccc3(0,0,0);
_labelCount.position = ccp(110, winSize.height - 16);
[self addChild:_labelCount z:2];
(In update:)
_bodyCount++;
NSString* bodyCountString = [NSStringstringWithFormat:@"%d", _bodyCount];!
[_labelCountsetString:bodyCountString];

62. Step 8: Adding Body Count

63. Step 9: Adding Sound & Music
(In init)
! // Start background music, set lower volume
SimpleAudioEngine.sharedEngine.backgroundMusicVolume = 0.4f;
! [[SimpleAudioEnginesharedEngine] playBackgroundMusic:@"explosive_attack.mp3"];
(In ccTouchesEnded)
// Play sound effect on every shot and on death
!
[[SimpleAudioEnginesharedEngine] playEffect:@"shot.mp3"];
!(In update: where the target is killed)
! [[SimpleAudioEnginesharedEngine] playEffect:@"death.mp3"];

64. Let’s Play!

65. KillTime 2.0
Enemies can move and attack
Joypad
Move our hero
Different weapons, power ups and health
Game menu and high scores
Levels
Save/Load Game
Refactor code (More scenes and layers)

66. More stuff to explore
Physics Engines - Chipmunk and Box2D
Particle System
Tilemaps
Menu Interface

67. Where can you learn more
Cocos2D Demo Library (Comes with Cocos)
Wiki: http://cocos2d-iphone.org/wiki
Ray Wenderlich: http://www.raywenderlich.com
Steffen Itterheim: http://learn-cocos2d.com
Sapus Tongue Source Code: http://www.sapusmedia.com/source

68. Thank You!
SAALIS UMER