Core Animation学习----CAkeyframeAnimation

CAkeyframeAnimation：提供了关键帧动画的支持。你可以为层属性指定key path来使其产生动画，这个数组的值保存了动画每个阶段的值，同时还有key frame的次数和时间函数。在动画运行的时候，数组中的每个值就会被轮流进行插值使用。

- (void)viewDidLoad {


    [super viewDidLoad];


    


    self.title = [[self class] displayName];


    


    self.view.backgroundColor = [UIColor blackColor];


    


    CGFloat radius = 30.0f;


    CGFloat diameter = radius * 2;


    CGPoint arcCenter = CGPointMake(radius, radius);


    


    // Create a UIBezierPath for Pacman's open state


    pacmanOpenPath = [[UIBezierPath bezierPathWithArcCenter:arcCenter


                                                               radius:radius 


                                                           startAngle:DEGREES_TO_RADIANS(35) 


                                                             endAngle:DEGREES_TO_RADIANS(315)


                                                            clockwise:YES] retain];    










    [pacmanOpenPath addLineToPoint:arcCenter];


    [pacmanOpenPath closePath];


    


    // Create a UIBezierPath for Pacman's close state


    pacmanClosedPath = [[UIBezierPath bezierPathWithArcCenter:arcCenter


                                                               radius:radius 


                                                           startAngle:DEGREES_TO_RADIANS(1) 


                                                             endAngle:DEGREES_TO_RADIANS(359) 


                                                            clockwise:YES] retain];


    [pacmanClosedPath addLineToPoint:arcCenter];


    [pacmanClosedPath closePath];    


    


    // Create a CAShapeLayer for Pacman, fill with yellow


    shapeLayer = [CAShapeLayer layer];


    shapeLayer.fillColor = [UIColor yellowColor].CGColor;


    shapeLayer.path = pacmanClosedPath.CGPath;


    shapeLayer.strokeColor = [UIColor grayColor].CGColor;


    shapeLayer.lineWidth = 1.0f;


    shapeLayer.bounds = CGRectMake(0, 0, diameter, diameter);


    shapeLayer.position = CGPointMake(-40, -100);


    [self.view.layer addSublayer:shapeLayer];


    


    SEL startSelector = @selector(startAnimation);


    UIGestureRecognizer *recognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:startSelector];


    [self.view addGestureRecognizer:recognizer];


    [recognizer release];


    


    // start animation after short delay


    [self performSelector:startSelector withObject:nil afterDelay:1.0];


}






- (void)startAnimation {






    // Create CHOMP CHOMP animation


    CABasicAnimation *chompAnimation = [CABasicAnimation animationWithKeyPath:@"path"];


    chompAnimation.duration = 0.25;


    


    chompAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];


    chompAnimation.repeatCount = HUGE_VALF;


    chompAnimation.autoreverses = YES;


    // Animate between the two path values


    chompAnimation.fromValue = (id)pacmanClosedPath.CGPath;


    chompAnimation.toValue = (id)pacmanOpenPath.CGPath;


    


    [shapeLayer addAnimation:chompAnimation forKey:@"chompAnimation"];


    


    // Create digital '2'-shaped path


    UIBezierPath *path = [UIBezierPath bezierPath];


    [path moveToPoint:CGPointMake(-40, 100)];


    [path addLineToPoint:CGPointMake(360, 100)];


    [path addLineToPoint:CGPointMake(360, 200)];


    [path addLineToPoint:CGPointMake(-40, 200)];


    [path addLineToPoint:CGPointMake(-40, 300)];


    [path addLineToPoint:CGPointMake(360, 300)];


    


    CAKeyframeAnimation *moveAnimation = [CAKeyframeAnimation animationWithKeyPath:@"position"];


    moveAnimation.path = path.CGPath;


    moveAnimation.duration = 8.0f;


    // Setting the rotation mode ensures Pacman's mouth is always forward.  This is a very convenient CA feature.


    moveAnimation.rotationMode = kCAAnimationRotateAuto;


    [shapeLayer addAnimation:moveAnimation forKey:@"moveAnimation"];}