Core Animation一些Demo总结 （动态切换图片、大转盘、图片折叠、进度条等动画效果）

前一篇总结了Core Animation的一些基础知识，这一篇主要是Core Animation 的一些应用，涉及到CAShapeLayer、CAReplicatorLayer等图层的知识。

先看效果图：

1、切换图片：
     

2、彩票转盘

3、图片折叠

4、进度条旋转

5、粒子效果

一、切换图片

看起来很复杂的动画，通过少量的计算和编码就可以简单的实现。要做到这一步，必须是需要研究iOS开发中的Core Animation和Core Graphics框架的。日常工作中，对于很多东西不求甚解，只是拿过来用，甚至都不研究、封装一下别人代码，这种做法是很不好的。我喜欢自己造*，*造多了，开发经验与思维也就提升上去了。

这个动画实现是比较简单的，利用了CABasicAnimation、CAKeyframeAnimation和CAAnimationGroup。看似是两张图片各自有着自己不同的动画，实际不过是一个动画方法，其平移方向与旋转角度的不同。

我是用了CABasicAnimation设置了view的zPosition值，CAKeyframeAnimation对象设计了图片的位移与旋转动画，然后将之放到CAAnimationGroup对象里面，开始动画。

这里有一个注意点，那就是Core Animation设置的动画位移、旋转、缩放都只是一个假象，实际上的view该怎么还是怎么样，并未真正有过变化。所以，在动画结束后，想要正确的效果，那么需要设置view的zPosition值，这个值越大，view越在前面（z轴方向上的“前面”）。

代码：

#import "ViewController.h"

@interface ViewController ()
@property (nonatomic, strong) NSMutableArray *images;
@property (nonatomic, assign) int currentIndex;

@property (weak, nonatomic) IBOutlet UIImageView *currentImageView;
@property (weak, nonatomic) IBOutlet UIImageView *behindImageView;

@end

@implementation ViewController

- (NSMutableArray *)images
{
    if (_images == nil) {
        _images = [NSMutableArray array];

        for (int i = 1; i <= 7; i++) {
            UIImage *image = [UIImage imageNamed: [NSString stringWithFormat:@"%d",i]];
            [_images addObject:image];
        }
    }
    return _images;
}

- (void)viewDidLoad
{
    [super viewDidLoad];

    self.currentIndex = 0;
    self.currentImageView.image = self.images[_currentIndex];
}

- (void)addAnimateWithPoint:(CGPoint )point angle:(CGFloat)angle fromZ:(CGFloat)fromZ toZ:(CGFloat)toZ view:(UIView *)view
{
    CABasicAnimation *zPosition = [[CABasicAnimation alloc] init];
    zPosition.keyPath = @"zPosition";
    zPosition.fromValue = @(fromZ);
    zPosition.toValue = @(toZ);
    zPosition.duration = 1.2;

    CAKeyframeAnimation *rotation = [[CAKeyframeAnimation alloc] init];
    rotation.keyPath = @"transform.rotation";
    rotation.values = @[@(0), @(angle), @(0)];
    rotation.duration = 2;
    rotation.timingFunctions = @[
                                 [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut],
                                 [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut]];

    CAKeyframeAnimation *position = [[CAKeyframeAnimation alloc] init];
    position.keyPath = @"position";
//    CGPointMake(110, -20)
    position.values = @[
                        [NSValue valueWithCGPoint:CGPointZero],
                        [NSValue valueWithCGPoint:point],
                        [NSValue valueWithCGPoint:CGPointZero]
                        ];

    position.timingFunctions = @[
                                 [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut],
                                 [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut]
                                 ];

    position.additive = YES;
    position.duration = 1.2;

    CAAnimationGroup *animateGroup = [[CAAnimationGroup alloc] init];
    animateGroup.animations = @[zPosition, rotation, position];
//    animateGroup.beginTime = 0.5;
    animateGroup.delegate = self;
    animateGroup.duration = 1.2;
    [animateGroup setValue:view forKey:@"view"];
    [view.layer addAnimation:animateGroup forKey:nil];

    view.layer.zPosition = toZ;

}

- (void)animationDidStop:(CAAnimation *)anim finished:(BOOL)flag
{
    CAAnimationGroup *group = [anim valueForKey:@"view"];
    if (group != nil) {
        self.currentImageView.image = self.images[_currentIndex];
        self.currentImageView.layer.zPosition = 1;
        self.behindImageView.image = nil;
        self.behindImageView.layer.zPosition = -1;
    }
}
- (IBAction)previous:(id)sender {
    self.currentIndex = (self.currentIndex + 1) % self.images.count;
    self.behindImageView.image = self.images[_currentIndex];

    [self addAnimateWithPoint:CGPointMake(-90, 20) angle:0.15 fromZ:-1 toZ:1 view:self.behindImageView];
    [self addAnimateWithPoint:CGPointMake(90, -20) angle:-0.15 fromZ:1 toZ:-1 view:self.currentImageView];
}

- (IBAction)next:(id)sender {
    self.currentIndex = (self.currentIndex + 6) % self.images.count;
    self.behindImageView.image = self.images[_currentIndex];
    [self addAnimateWithPoint:CGPointMake(-90, 20) angle:-0.15 fromZ:-1 toZ:1 view:self.behindImageView];
    [self addAnimateWithPoint:CGPointMake(90, -20) angle:0.15 fromZ:1 toZ:-1 view:self.currentImageView];
}
@end

Github地址：https://github.com/wzpziyi1/Core-AnimationTest-Two

二、彩票转盘

这个动画的实现主要难点在于Button的摆放，只要摆放好button，其他就是简单的添加动画的一个过程。

12个星座，那么需要12个button。在摆放它们的时候，我是将一个个button的anchorPoint设置为(0.5, 1)，将button的position设置为中心圆的圆心，然后设置transform来旋转它们，是的达到围绕一个圆摆放的目的。

需要知道的是，一般来说，控件的anchorPoint就是控件的中心点，所以在我们做旋转、平移等操作的时候，也就是在围绕中心点的一系列操作。但是，很多时候，只是围绕中心点来设置动画的话，会很复杂，CALayer提供了一个anchorPoint属性，可以让我们*的改变其数值，从而实现比较复杂的动画。

还有就是button的点击事件，事实上由于一个扇形区域是上边大，下边小，要是不做相应的限制，当用户点击下面的区域时，很可能不是选中当前的button，因此要做一定的限制。这里我是自定义了一个button，在里面重写了hitTest: WwthEvent: 方法，这个方法可以设置你所要监听事件的区域范围。

代码：

#import "ZYWheelView.h"

#define ZYImageW 40

#define ZYImageH 46

@interface ZYButton : UIButton

@end

@implementation ZYButton

/**
 *  重写此方法，截取button的点击
 *
 */
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event
{
    CGFloat btnW = self.bounds.size.width;
    CGFloat btnH = self.bounds.size.height;

    CGFloat x = 0;
    CGFloat y = btnH / 2;
    CGFloat w = btnW;
    CGFloat h = y;
    CGRect rect = CGRectMake(x, y, w, h);
    if (CGRectContainsPoint(rect, point)) {
        return nil;
    }else{
        return [super hitTest:point withEvent:event];
    }
}

- (CGRect)imageRectForContentRect:(CGRect)contentRect
{
    CGFloat imageX = (contentRect.size.width - ZYImageW ) * 0.5;
    CGFloat imageY = 18;
    return CGRectMake(imageX, imageY, ZYImageW, ZYImageH);
}

- (void)setHighlighted:(BOOL)highlighted
{

}

@end

@interface ZYWheelView ()
@property (weak, nonatomic) IBOutlet UIImageView *wheelView;

@property (nonatomic, weak) UIButton *lastSelectedBtn;

@property (nonatomic, strong) CADisplayLink *timer;
@end

@implementation ZYWheelView

+ (instancetype)wheelView
{
    return [[[NSBundle mainBundle] loadNibNamed:@"ZYWheelView" owner:nil options:nil] lastObject];
}

- (void)awakeFromNib
{
    self.wheelView.userInteractionEnabled = YES;
    CGFloat angle = 2 * M_PI / 12.0;

    UIImage *normalImage = [UIImage imageNamed:@"LuckyAstrology"];
    UIImage *selectedImage = [UIImage imageNamed:@"LuckyAstrologyPressed"];

    for (int bi = 0; bi < 12; bi++) {
        ZYButton *btn = [[ZYButton alloc] init];
        [btn setBackgroundImage:[UIImage imageNamed:@"LuckyRototeSelected"] forState:UIControlStateSelected];

//        切割图片,将切割好的图片设置到按钮上
        // CGImage中rect是当做像素来使用
        // UIKit 中是点坐标系
        // 坐标系的特点:如果在非retain屏上 1个点等于1个像素
        //   在retain屏上1个点等于2个像素
        CGFloat imageH = ZYImageH * [UIScreen mainScreen].scale;
        CGFloat imageW = ZYImageW * [UIScreen mainScreen].scale;
        CGFloat imageY = 0;
        CGFloat imageX = bi * imageW;
        CGRect rect = CGRectMake(imageX, imageY, imageW, imageH);

        CGImageRef normalRef = CGImageCreateWithImageInRect(normalImage.CGImage, rect);
        CGImageRef selectedRef = CGImageCreateWithImageInRect(selectedImage.CGImage, rect);

        [btn setImage:[UIImage imageWithCGImage:normalRef] forState:UIControlStateNormal];
        [btn setImage:[UIImage imageWithCGImage:selectedRef] forState:UIControlStateSelected];

        btn.bounds = CGRectMake(0, 0, 58, 143);

        btn.layer.anchorPoint = CGPointMake(0.5, 1);

        btn.layer.position = CGPointMake(self.frame.size.width * 0.5, self.frame.size.height * 0.5);

        btn.transform = CGAffineTransformMakeRotation(angle * bi);

        [btn addTarget:self action:@selector(clickBtn:) forControlEvents:UIControlEventTouchUpInside];

        [self.wheelView addSubview:btn];
    }
    [self startRotating];
}

- (void)startRotating
{

    if (self.timer) return;
    self.timer = [CADisplayLink displayLinkWithTarget:self selector:@selector(updateTimer)];
    [self.timer addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSRunLoopCommonModes];
}

- (void)stopRotating
{
    [self.timer invalidate];
    self.timer = nil;
}

- (void)clickBtn:(UIButton *)btn
{
    self.lastSelectedBtn.selected = NO;
    btn.selected = YES;
    self.lastSelectedBtn = btn;
}

- (IBAction)clickCenterBtn:(id)sender {

    self.userInteractionEnabled = NO;
    [self stopRotating];
    CABasicAnimation *basicAnimation = [CABasicAnimation animationWithKeyPath:@"transform.rotation"];
    basicAnimation.toValue = @(M_PI * 2 * 5);
    basicAnimation.duration = 2;
    basicAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
//    basicAnimation.removedOnCompletion = NO;
//    basicAnimation.fillMode = kCAFillModeForwards;
    basicAnimation.delegate = self;
    [self.wheelView.layer addAnimation:basicAnimation forKey:nil];

}

- (void)animationDidStop:(CAAnimation *)anim finished:(BOOL)flag
{
    self.userInteractionEnabled = YES;

    // 根据选中的按钮获取旋转的度数,
    // 通过transform获取角度
    CGFloat angle = atan2(self.lastSelectedBtn.transform.b, self.lastSelectedBtn.transform.a);

    // 从实际上旋转转盘
    self.wheelView.transform = CGAffineTransformMakeRotation(-angle);

    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(1 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        [self startRotating];
    });

}

- (void)updateTimer
{
    self.wheelView.transform = CGAffineTransformRotate(self.wheelView.transform, M_PI / 200);
}

- (void)dealloc
{
    [self stopRotating];
}

@end

Github地址：https://github.com/wzpziyi1/Core-AnimationTest-Three

3、图片折叠

这个效果看起来很炫酷，但实际做起来是比较简单的。需要三个View，两个UIImageView，一个接受拖拽action的View。CALayer里面有个contentRect属性，它可以设置layer里面的显示内容，利用这个属性，我们可以做在下载图片时，下载一点展示一点的效果。 在这里，我用这个属性来这是两张UIImageView各自展示一半的图片，然后将这两张ImageView拼接在一起，显示完整的图片。

在一个覆盖这张完整图片的View上添加拖拽手势，以实现动画过程。

这里有一个新的图层需要学习下，CAGradientLayer，它是用来做颜色渐变的，用法与CALayer的用法相似：

属性代码：

CAGradientLayer *gradientLayer = [CAGradientLayer layer];
    gradientLayer.frame = self.bottomView.bounds;

    gradientLayer.opacity = 0;

    gradientLayer.colors = @[(id)[UIColor clearColor].CGColor, (id)[UIColor blackColor].CGColor];

    self.gradientLayer = gradientLayer;

    [self.bottomView.layer addSublayer:gradientLayer];

    // 设置渐变颜色
    //    gradientL.colors = @[(id)[UIColor redColor].CGColor,(id)[UIColor greenColor].CGColor,(id)[UIColor yellowColor].CGColor];

    // 设置渐变定位点
    //    gradientL.locations = @[@0.1,@0.4,@0.5];

    // 设置渐变开始点，取值0~1
    //    gradientL.startPoint = CGPointMake(0, 1);

设置好之后，在pan手势的方法里面不断改变gradientLayer的opacity即可达到想要的效果。

CATransform3D有个m34属性，可以设置透视度，一般将这个值设置为- 1 / 500.0，特定需求可以微调这个值。

代码：

#import "ViewController.h"

@interface ViewController ()
@property (weak, nonatomic) IBOutlet UIImageView *topView;
@property (weak, nonatomic) IBOutlet UIImageView *bottomView;
@property (weak, nonatomic) IBOutlet UIView *containView;

@property (nonatomic, weak) CAGradientLayer *gradientLayer;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    [self setupOtherView];

    //设置渐变的阴影
    [self setupShadow];
}

- (void)setupOtherView
{
    //设置contentsRect用来表示图片显示的大小，可以做边下载边显示的UI效果,取值是(0--1)
    self.topView.layer.contentsRect = CGRectMake(0, 0, 1, 0.5);
    self.topView.layer.anchorPoint = CGPointMake(0.5, 1);

    self.bottomView.layer.contentsRect = CGRectMake(0, 0.5, 1, 0.5);
    self.bottomView.layer.anchorPoint = CGPointMake(0.5, 0);

    UIPanGestureRecognizer *gesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(pan:)];
    [self.containView addGestureRecognizer:gesture];
}

- (void)setupShadow
{
    CAGradientLayer *gradientLayer = [CAGradientLayer layer];
    gradientLayer.frame = self.bottomView.bounds;

    gradientLayer.opacity = 0;

    gradientLayer.colors = @[(id)[UIColor clearColor].CGColor, (id)[UIColor blackColor].CGColor];

    self.gradientLayer = gradientLayer;

    [self.bottomView.layer addSublayer:gradientLayer];

    // 设置渐变颜色
    //    gradientL.colors = @[(id)[UIColor redColor].CGColor,(id)[UIColor greenColor].CGColor,(id)[UIColor yellowColor].CGColor];

    // 设置渐变定位点
    //    gradientL.locations = @[@0.1,@0.4,@0.5];

    // 设置渐变开始点，取值0~1
    //    gradientL.startPoint = CGPointMake(0, 1);
}

- (void)pan:(UIPanGestureRecognizer *)recognizer
{
    CGFloat y = [recognizer translationInView:self.containView].y;

    if (y >= 300) y = 300;

    if (y <= -300) y = -300;

    // 旋转角度,往下逆时针旋转
    CGFloat angle = -y / 320.0 * M_PI;

    self.topView.layer.transform = CATransform3DIdentity;

    CATransform3D transfrom = CATransform3DIdentity;

    transfrom.m34 = -1 / 500.0;

    self.topView.layer.transform = CATransform3DRotate(transfrom, angle, 1, 0, 0);

    self.gradientLayer.opacity = y / 300.0;

    if (recognizer.state == UIGestureRecognizerStateEnded) {

        // 弹簧效果的动画
        // SpringWithDamping:弹性系数,越小，弹簧效果越明显
        [UIView animateWithDuration:0.5 delay:0 usingSpringWithDamping:0.3 initialSpringVelocity:11 options:UIViewAnimationOptionCurveEaseInOut animations:^{
            self.topView.layer.transform = CATransform3DIdentity;
            self.gradientLayer.opacity = 0;
        } completion:nil];
    }
}

@end

Github地址：https://github.com/wzpziyi1/Core-AnimationTest-Four

4、旋转进度条

圆圈旋转一般都是放在HUD上吧。记得以前我也做过一个类似的功能，那时候还没现在这样的知识储备，只能是用CAKeyframeAnimation做，让美工做出了一根顶部是一个小白点，除此之外，很长的那部分是为clearColor的小矩形，然后我设置它的anchorPoint，给 CAKeyframeAnimation添加一个圆形的path，然后围绕这个path旋转，做是勉强做出来，但是很不好看吧。

现在可以有更好的选择了，CAReplicatorLayer（复制图层）。我们可以在复制图层里面添加一个instance图层，如果设置了复制图层的instanceCount，假如让instanceCount == 5， 那么复制图层会自动帮我们复制5个跟instance图层一样的图层（事实上，我们可以在一开始就给instance图层设置动画，那么在复制的时候，一样会把动画也复制过来），除此之外，还可以设置复制图层里面的instance图层的transfrom，从而实现一定的布局。复制图层里面还有一个instanceDelay，它表示延迟多少时间开始动画等等。

这个Demo就是用了上面所说的实现的，代码：

#import "ViewController.h"

@interface ViewController ()

@property (weak, nonatomic) IBOutlet UIView *containView;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    [self setupReplicatorLayerAndAnimation];
}

- (void)setupReplicatorLayerAndAnimation
{
    CAReplicatorLayer *replicatorLayer = [CAReplicatorLayer layer];
    replicatorLayer.frame = self.containView.layer.bounds;
    [self.containView.layer addSublayer:replicatorLayer];

    CALayer *layer = [CALayer layer];
    layer.frame = CGRectMake(self.containView.frame.size.width * 0.5, 20, 16, 16);
    layer.backgroundColor = [UIColor redColor].CGColor;
    layer.cornerRadius = layer.frame.size.width / 2;

    //这一句可以将初始过程移除掉
    layer.transform = CATransform3DMakeScale(0, 0, 0);

    [replicatorLayer addSublayer:layer];

    replicatorLayer.instanceCount = 22;

    CABasicAnimation *basicAn = [CABasicAnimation animationWithKeyPath:@"transform.scale"];

    basicAn.fromValue = @1;
    basicAn.toValue = @0;

    basicAn.duration = 1;

    basicAn.repeatCount = MAXFLOAT;

    [layer addAnimation:basicAn forKey:nil];

    replicatorLayer.instanceDelay = basicAn.duration / (double)replicatorLayer.instanceCount;

    replicatorLayer.instanceTransform = CATransform3DMakeRotation(2 * M_PI / replicatorLayer.instanceCount, 0, 0, 1);
}

@end

Github地址：https://github.com/wzpziyi1/Core-Animation-Test-Five

5、粒子效果

这个东西就是CAReplicatorLayer（复制图层）和Core Graphics的结合吧，我是采用UIBezierPath来绘制线条，然后将绘制好的path赋值给小球的animation路径，然后将小球添加到复制图层，设置下instanceCount，设置下延迟时间，效果就出来了。

代码：

#import "ZYDrawView.h"

@interface ZYDrawView ()
@property (nonatomic, strong) UIBezierPath *bezierPath;

@property (nonatomic, weak) CAReplicatorLayer *replicatorLayer;

@property (nonatomic, weak) CALayer *norLayer;
@end

static int _count = 0;

@implementation ZYDrawView

- (UIBezierPath *)bezierPath
{
    if (_bezierPath == nil) {
        _bezierPath = [[UIBezierPath alloc] init];
    }
    return _bezierPath;
}

- (void)awakeFromNib
{
    CAReplicatorLayer *replicatorLayer = [CAReplicatorLayer layer];
    replicatorLayer.frame = self.bounds;
    [self.layer addSublayer:replicatorLayer];

    CALayer *layer = [CALayer layer];

    layer.frame = CGRectMake(0, -200, 10, 10);
    layer.cornerRadius = layer.frame.size.width * 0.5;
    layer.backgroundColor = [UIColor redColor].CGColor;

    [replicatorLayer addSublayer:layer];

    self.replicatorLayer = replicatorLayer;
    self.norLayer = layer;
}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    CGPoint curPoint = [[touches anyObject] locationInView:self];

    [self.bezierPath moveToPoint:curPoint];

}

- (void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    _count++;
    CGPoint curPoint = [[touches anyObject] locationInView:self];

    [self.bezierPath addLineToPoint:curPoint];

    [self setNeedsDisplay];
}

- (void)startAnimation
{
    CAKeyframeAnimation *keyframeAn = [CAKeyframeAnimation animationWithKeyPath:@"position"];

    keyframeAn.path = self.bezierPath.CGPath;

    keyframeAn.duration = 4;

    keyframeAn.repeatCount = MAXFLOAT;

    [self.norLayer addAnimation:keyframeAn forKey:nil];

    self.replicatorLayer.instanceCount = _count;

    self.replicatorLayer.instanceDelay = 0.1;
}

- (void)reDraw
{
    _bezierPath = nil;
    _count = 1;
    [self.norLayer removeAllAnimations];

    [self setNeedsDisplay];
}

- (void)drawRect:(CGRect)rect
{
    [self.bezierPath stroke];
}

@end

Github地址：https://github.com/wzpziyi1/Core-Animation-Test-Six