Making things Move on the iPhone

Making Things Move
on the iPhone
Keith Peters
www.bit-101.com

Wednesday, March 4, 2009

www.bit-101.com/
360iDev/
presentation.zip


CoreAnimation


Background


Background
2005


Background
2005
2007


Background
2005
2007
2008


What is Animation?


Coded Animation


Coded Animation
Apply a
rule


Coded Animation
Apply a
rule

Change
something


Coded Animation
Apply a
rule

Update Change
the screen something


Make something
to move


Make something
to move

(project ﬁles: Animation101)


// interface
UIImageView *ball;

// viewDidLoad
ball = [[UIImageView alloc] initWithImage:
[UIImage imageNamed:@quot;ball.pngquot;]];
[self.view addSubview:ball];


NSTimer


NSTimer
[NSTimer
scheduledTimerWithTimeInterval:1.0/60.0
target:self
selector:@selector(onTimer)
userInfo:nil
repeats:YES];


Moving UIViews


Moving UIViews

• view.center


Moving UIViews

• view.center
• view.transform


Moving UIViews

• view.center
• view.transform
• view.frame


// interface
float x;
float y;

// viewDidLoad
x = 50.0;
y = 50.0;


ball.center = CGPointMake(x, y);
x += 2.0;
y += 3.0;


ball.frame = CGRectMake(x, y, width, height);
x += 2.0;
y += 3.0;


ball.transform =
CGAffineTransformMakeTranslation(x, y);
x += 2.0;
y += 3.0;


ball.transform =
CGAffineTransformTranslate(
ball.transform, 2.0, 3.0);


Which is fastest?


Which is fastest?

• view.center


Which is fastest?

• view.center
• view.transform (~2-3x)


Which is fastest?

• view.center
• view.transform (~2-3x)
• view.frame (~2-3x)


Velocity

(project ﬁles:Velocity)


Velocity

+
(project ﬁles:Velocity)


speed
and
direction


speed
and
direction
y velocity

x velocity


- y velocity

- x velocity + x velocity

+ y velocity


// interface:
float vx;
float vy;


// interface:
float vx;
float vy;

// viewDidLoad:
vx = 2.0;
vy = 3.0;


// interface:
float vx;
float vy;

// viewDidLoad:
vx = 2.0;
vy = 3.0;

// onTimer:
x += vx;
y += vy;


speed

angle

(project ﬁles: AngularVelocity)


y velocity
speed =
sin(angle)
x
speed
angle
x velocity = cos(angle) x speed
(project ﬁles: AngularVelocity)


// interface:
float angle;
float speed;


// interface: // viewDidLoad:
float angle; angle = 45.0;
float speed; speed = 4.0;


float angle; angle = 45.0;
float speed; speed = 4.0;

// onTimer:
x += cos(angle * M_PI / 180.0) * speed;
y += sin(angle * M_PI / 180.0) * speed;


Acceleration

(project ﬁles: Acceleration)


Acceleration

+
(project ﬁles: Acceleration)


// interface:
float ax;
float ay;


float ax; ax = 0.07;
float ay; ay = 0.1;


float ax; ax = 0.07;
float ay; ay = 0.1;

// onTimer:
x += vx;
y += vy;
vx += ax;
vy += ay;


Bouncing

(project ﬁles: Bouncing)


-x velocity y velocity

y velocity
x velocity


// interface:
float bounce;


// interface:
float bounce;

// viewDidLoad:
bounce = -1.0;


x += vx;
y += vy;
if(x > 300) // 320 - radius (20)
{
x = 300;
vx *= bounce;
}
else if(x < 20) // 0 + radius
{
x = 20;
vx *= bounce;
}


if(y > 440) // 460 - radius

{
y = 440;
vy *= bounce;
}
else if(y < 20) // 0 + radius
{
y = 20;
vy *= bounce;
}


Gravity

acceleration
(+y)


// interface:
float gravity;


// interface:
float gravity;

// viewDidLoad:
gravity = 0.5;


// interface:
float gravity;

// viewDidLoad:
gravity = 0.5;

// onTimer:
vy += gravity;


acceleration.y

acceleration.x


@interface GravityViewController :
UIViewController <UIAccelerometerDelegate>
{
UIImageView *ball;
float x;
float y;
float vx;
float vy;
float bounce;
CGPoint gravity;
}


// viewDidLoad
gravity = CGPointZero;
[[UIAccelerometer sharedAccelerometer]
setDelegate:self];


// viewDidLoad
setDelegate:self];

- (void)accelerometer:(UIAccelerometer *)accelerometer
didAccelerate:(UIAcceleration *)acceleration
{
gravity = CGPointMake(acceleration.x,
-acceleration.y);
}


// viewDidLoad
setDelegate:self];

- (void)accelerometer:(UIAccelerometer *)accelerometer
didAccelerate:(UIAcceleration *)acceleration
{
gravity = CGPointMake(acceleration.x,
-acceleration.y);
}

// onTimer
vx += gravity.x;
vy += gravity.y;


Do we still have time?


Dragging and Throwing


// interface
BOOL dragging;


// interface // viewDidLoad
BOOL dragging; dragging = NO;


// interface // viewDidLoad
BOOL dragging; dragging = NO;

- (void)onTimer
{
if(!dragging)
{
...
}
}


- (void)touchesBegan:(NSSet *)touches
withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
CGPoint point = [touch locationInView:self.view];
float dx = point.x - x;
float dy = point.y - y;
float dist = sqrt(dx * dx + dy * dy);
if(dist < 20)
{
dragging = YES;
x = point.x;
y = point.y;
vx = 0;
vy = 0;
}
}


- (void)touchesEnded:(NSSet *)touches
{
dragging = NO;
}


- (void)touchesMoved:(NSSet *)touches
{
if(dragging)
{
UITouch *touch = [touches anyObject];
CGPoint point = [touch locationInView:self.view];
vx = point.x - x;
vy = point.y - y;
x = point.x;
y = point.y;
ball.center = point;
}
}


Thank you
• Keith Peters
• kp@bit-101.com
• www.bit-101.com
• www.wickedpissahgames.com
• www.bit-101.com/360iDev/presentation.zip


Making things Move on the iPhone

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