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。我喜欢自己造轮子，轮子造多了，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

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，可以让我们自由的改变其数值，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

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

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

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 *)touches withEvent:(UIEvent *)event

{

CGPoint curPoint = [[touches anyObject] locationInView:self];

[self.bezierPath moveToPoint:curPoint];

}

- (void)touchesMoved:(NSSet *)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

以上内容是小编给大家介绍的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)，希望对大家以上帮助！