Core Animation之多种动画效果

前面介绍了Core Animation基础知识，还有CALayer的简单使用，最终还是有要动画的滴，这里列出几个动画效果，参考下能加深对Core Animation的认识和理解

1、把图片移到右下角变小透明

使用CAAnimationGroup叠加动画效果，就是下面按钮《把图片移到右下角变小透明》描述的效果：

、

上面三个图是动画的三个状态，实现代码如下：

- (void)viewDidLoad

{

    [super viewDidLoad];

    self.imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"snaguosha.png"]];

    self.imageView.frame = CGRectMake(10, 10, 128, 192);

    [self.view addSubview:self.imageView];

 }

- (IBAction)tranAction:(id)sender {

    CGPoint fromPoint = self.imageView.center;

    //路径曲线

    UIBezierPath *movePath = [UIBezierPath bezierPath];

    [movePath moveToPoint:fromPoint];

    CGPoint toPoint = CGPointMake(300, 460);

    [movePath addQuadCurveToPoint:toPoint

                     controlPoint:CGPointMake(300,0)];

    //关键帧

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

    moveAnim.path = movePath.CGPath;

    moveAnim.removedOnCompletion = YES;

    //旋转变化

    CABasicAnimation *scaleAnim = [CABasicAnimation animationWithKeyPath:@"transform"];

    scaleAnim.fromValue = [NSValue valueWithCATransform3D:CATransform3DIdentity];

    //x，y轴缩小到0.1,Z 轴不变

    scaleAnim.toValue = [NSValue valueWithCATransform3D:CATransform3DMakeScale(0.1, 0.1, 1.0)];

    scaleAnim.removedOnCompletion = YES;

    //透明度变化

    CABasicAnimation *opacityAnim = [CABasicAnimation animationWithKeyPath:@"alpha"];

    opacityAnim.fromValue = [NSNumber numberWithFloat:1.0];

    opacityAnim.toValue = [NSNumber numberWithFloat:0.1];

    opacityAnim.removedOnCompletion = YES;

    //关键帧，旋转，透明度组合起来执行

    CAAnimationGroup *animGroup = [CAAnimationGroup animation];

    animGroup.animations = [NSArray arrayWithObjects:moveAnim, scaleAnim,opacityAnim, nil];

    animGroup.duration = 1;

    [self.imageView.layer addAnimation:animGroup forKey:nil];

}

代码解析：上面关键帧设置了动画的路径，scaleAnim设置了缩小，opacityAnim设置了透明度的变化。把三个动画组合到：animGroup。

在把animGroup添加到imageView.layer层的动画里。于是动画效果就有了。

2、旋转并向右移动

- (IBAction)RightRotateAction:(id)sender {

    CGPoint fromPoint = self.imageView.center;

    UIBezierPath *movePath = [UIBezierPath bezierPath];

    [movePath moveToPoint:fromPoint];

    CGPoint toPoint = CGPointMake(fromPoint.x +100 , fromPoint.y ) ;

    [movePath addLineToPoint:toPoint];

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

    moveAnim.path = movePath.CGPath;

    CABasicAnimation *TransformAnim = [CABasicAnimation animationWithKeyPath:@"transform"];

    TransformAnim.fromValue = [NSValue valueWithCATransform3D:CATransform3DIdentity];

    //沿Z轴旋转

    TransformAnim.toValue = [NSValue valueWithCATransform3D: CATransform3DMakeRotation(M_PI,0,0,1)];

    //沿Y轴旋转

  //   scaleAnim.toValue = [NSValue valueWithCATransform3D: CATransform3DMakeRotation(M_PI,0,1.0,0)];

    //沿X轴旋转

//     TransformAnim.toValue = [NSValue valueWithCATransform3D: CATransform3DMakeRotation(M_PI,1.0,0,0)];

    TransformAnim.cumulative = YES;

    TransformAnim.duration =3;

    //旋转2遍，360度

    TransformAnim.repeatCount =2;

    self.imageView.center = toPoint;

    TransformAnim.removedOnCompletion = YES;

    CAAnimationGroup *animGroup = [CAAnimationGroup animation];

    animGroup.animations = [NSArray arrayWithObjects:moveAnim, TransformAnim, nil];

    animGroup.duration = 6;

    [self.imageView.layer addAnimation:animGroup forKey:nil];

}

代码解析:可能你没注意到，CATransform3DMakeRotation，这返回的是旋转的值。上面的动画效果里返回的是CATransform3DMakeScale缩放的值。
向右移动是因为关键帧使用了路径为直线的路径。

3、旋转并消除边缘锯齿

- (IBAction)Rotate360Action:(id)sender {

    //图片旋转360度

    CABasicAnimation *animation = [ CABasicAnimation

                                   animationWithKeyPath: @"transform" ];

    animation.fromValue = [NSValue valueWithCATransform3D:CATransform3DIdentity];

    //围绕Z轴旋转，垂直与屏幕

    animation.toValue = [ NSValue valueWithCATransform3D:

                         CATransform3DMakeRotation(M_PI, 0, 0, 1.0) ];

    animation.duration = 3;

    //旋转效果累计，先转180度，接着再旋转180度，从而实现360旋转

    animation.cumulative = YES;

    animation.repeatCount = 2;

    //在图片边缘添加一个像素的透明区域，去图片锯齿

    CGRect imageRrect = CGRectMake(0, 0, self.imageView.frame.size.width, self.imageView.frame.size.height);

    UIGraphicsBeginImageContext(imageRrect.size);

    [self.imageView.image drawInRect:CGRectMake(1,1,self.imageView.frame.size.width-2,self.imageView.frame.size.height-2)];

    self.imageView.image = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    [self.imageView.layer addAnimation:animation forKey:nil];

}

如果你仔细观察，会看到第二个动画里在旋转时，图片边缘是有锯齿的，如何消除呢？在图片边缘添加一个像素的透明区域，去图片锯齿。

UIGraphicsBeginImageContext 开始图片内容

UIGraphicsGetImageFromCurrentImageContext 获取当前内容作为图片，

UIGraphicsEndImageContext结束。是和UIGraphicsBeginImageContext配套使用的。

4、吃豆人动画

这个有点复杂，首先说下实现的步骤：

画一个吃豆人开口的路径：pacmanOpenPath
画一个吃豆人闭口的路径：pacmanClosedPath
新建一个闭口的吃豆人头的层：shapeLayer
把开口和闭口路径设置成CABasicAnimation *chompAnimation动画的起点和终点，这样循环就能出现咬牙的动画了。
最后设置一个路径为关键帧，让吃豆人在这条路径上行动。

代码如下：

- (void)animationInit

{

    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];

    [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];

    [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];

}

- (void)startAnimation {

    // 创建咬牙动画

    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(0, 100)];

    [path addLineToPoint:CGPointMake(300, 100)];

    [path addLineToPoint:CGPointMake(300, 200)];

    [path addLineToPoint:CGPointMake(0, 200)];

    [path addLineToPoint:CGPointMake(0, 300)];

    [path addLineToPoint:CGPointMake(300, 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"];

}

- (void)viewDidLoad

{

    [super viewDidLoad];

    [self animationInit];

}

还需要添加一个宏：

#define DEGREES_TO_RADIANS(x) (3.14159265358979323846 * x / 180.0) 计算角度转换

添加了个手势，点一下屏幕，吃豆人就动起来了。效果：

原作者，容芳志 (http://blog.csdn.net/totogo2010)