最近總結(jié)一下CoreAnimation的基本知識(shí)。。绽昼。（ CALayer Animatable Properties）

Core Animation，中文翻譯為核心動(dòng)畫须蜗，它是一組非常強(qiáng)大的動(dòng)畫處理API硅确，使用它能做出非常炫麗的動(dòng)畫效果目溉，而且往往是事半功倍。也就是說菱农，使用少量的代碼就可以實(shí)現(xiàn)非常強(qiáng)大的功能缭付。
Core Animation可以用在Mac OS X和iOS平臺(tái)。
Core Animation的動(dòng)畫執(zhí)行過程都是在后臺(tái)操作的循未，不會(huì)阻塞主線程陷猫。
要注意的是，Core Animation是直接作用在CALayer上的的妖，并非UIView绣檬。

先上一張圖，看一下核心動(dòng)畫中的基本類和他們之間的關(guān)系嫂粟，箭頭表示繼承關(guān)系娇未。

WechatIMG7.jpeg

下面分一下幾點(diǎn)介紹

• 1.CAAnimation
• 2.CAPropertyAnimation
• 3.CABasicAnimation 基本動(dòng)畫
• 4.CAKeyframeAnimation 關(guān)鍵幀動(dòng)畫
• 5.CATransition 轉(zhuǎn)場(chǎng)動(dòng)畫
• 6.CAAnimationGroup 動(dòng)畫組

1、CAAnimation

CAAnimation 是核心動(dòng)畫中的基礎(chǔ)抽象類星虹，其他的都是繼承自他來使用忘蟹。

CAAnimation
provides the basic support for the [CAMediaTiming] and [CAAction]protocols. 
You do not create instance of
[CAAnimation]: to animate Core Animation layers or SceneKit objects, 
create instances of the concrete subclasses [CABasicAnimation], 
[CAKeyframeAnimation], [CAAnimationGroup], or [CATransition]

CAAnimation遵循< CAMediaTiming >和< CAAction >協(xié)議，不能直接使用CAAnimation去實(shí)現(xiàn)動(dòng)畫效果搁凸，而是使用它的子類CABasicAnimation 、CAKeyframeAnimation狠毯、CAAnimationGroup护糖、CATransition。

CAMediaTiming
可以調(diào)整動(dòng)畫的持續(xù)時(shí)間嚼松、重復(fù)次數(shù)嫡良、動(dòng)畫的速度等。

CAAction
通過響應(yīng)動(dòng)作的方法來實(shí)現(xiàn)動(dòng)畫

看一下CAAnimation里面的API

+ (nullable id)defaultValueForKey:(NSString *)key;
類方法：根據(jù)相對(duì)的屬性key返回屬性值献酗，有點(diǎn)類似字典

- (BOOL)shouldArchiveValueForKey:(NSString *)key;
根據(jù)相對(duì)的屬性key該屬性的值返回是否可以歸檔寝受。

屬性（部分屬性是遵循CAMediaTiming協(xié)議中的）

fillMode屬性

• kCAFillModeForwards 當(dāng)動(dòng)畫結(jié)束后，layer會(huì)一直保持著動(dòng)畫最后的狀態(tài)惭墓，即動(dòng)畫停止的狀態(tài),不過要配合removedOnCompletion屬性設(shè)置為NO使用才有效果坛梁，不然沒效果。

• kCAFillModeBackwards 在動(dòng)畫開始前腊凶，只需要將動(dòng)畫加入了一個(gè)layer划咐，layer便立即進(jìn)入動(dòng)畫的初始狀態(tài)并等待動(dòng)畫開始。動(dòng)畫結(jié)束后钧萍，layer會(huì)恢復(fù)到之前的狀態(tài)

• kCAFillModeBoth 這個(gè)其實(shí)就是上面兩個(gè)的合成.動(dòng)畫加入后開始之前褐缠，layer便處于動(dòng)畫初始狀態(tài)，動(dòng)畫結(jié)束后layer保持動(dòng)畫最后的狀態(tài),不過要配合removedOnCompletion屬性設(shè)置為NO使用才有效果风瘦，不然沒效果

• kCAFillModeRemoved 這個(gè)是默認(rèn)值队魏，也就是說當(dāng)動(dòng)畫開始前和動(dòng)畫結(jié)束后，動(dòng)畫對(duì)layer都沒有影響万搔，動(dòng)畫結(jié)束后胡桨，layer會(huì)恢復(fù)到之前的狀態(tài)

timingFunction屬性

• kCAMediaTimingFunctionLinear（線性）：勻速，給你一個(gè)相對(duì)靜態(tài)的感覺
• kCAMediaTimingFunctionEaseIn漸進(jìn)）：動(dòng)畫緩慢進(jìn)入瞬雹，然后加速離開
• kCAMediaTimingFunctionEaseOut（漸出）：動(dòng)畫全速進(jìn)入昧谊，然后減速的到達(dá)目的地
• kCAMediaTimingFunctionEaseInEaseOut（漸進(jìn)漸出）：動(dòng)畫緩慢的進(jìn)入，中間加速酗捌，然后減速的到達(dá)目的地呢诬。這個(gè)是默認(rèn)的動(dòng)畫行為。
• kCAMediaTimingFunctionDefault：默認(rèn)的（線性）：勻速

CAAnimation的代理方法

@interface NSObject (CAAnimationDelegate)

/* Called when the animation begins its active duration. */
// 動(dòng)畫開始時(shí)調(diào)用
- (void)animationDidStart:(CAAnimation *)anim;

/* Called when the animation either completes its active duration or
 * is removed from the object it is attached to (i.e. the layer). 'flag'
 * is true if the animation reached the end of its active duration
 * without being removed. */
// 動(dòng)畫結(jié)束后調(diào)用
- (void)animationDidStop:(CAAnimation *)anim finished:(BOOL)flag;

@end

2.CAPropertyAnimation

CAPropertyAnimation繼承自CAAnimation,也是一個(gè)抽象類意敛，是CABasicAnimation和CAKeyframeAnimation的父類馅巷，不能直接使用來生成動(dòng)畫效果。

keyPath

通過指定CALayer的一個(gè)屬性名稱為keyPath（NSString類型）草姻，并且對(duì)CALayer的這個(gè)屬性的值進(jìn)行修改钓猬，達(dá)到相應(yīng)的動(dòng)畫效果。

/* Creates a new animation object with its `keyPath' property set to
 * 'path'. */

+ (instancetype)animationWithKeyPath:(nullable NSString *)path;

/* The key-path describing the property to be animated. */

@property(nullable, copy) NSString *keyPath;

3.CABasicAnimation 基本動(dòng)畫

繼承自CAPropertyAnimation账月，基本動(dòng)畫。主要的效果是keyPath里面的澳迫，指定keyPath相應(yīng)屬性的初始值和keyPath相應(yīng)屬性的結(jié)束值局齿。然后執(zhí)行動(dòng)畫。

動(dòng)畫過程說明：
隨著動(dòng)畫的進(jìn)行橄登，在長(zhǎng)度為duration的持續(xù)時(shí)間內(nèi)抓歼，keyPath相應(yīng)屬性的值從fromValue漸漸地變?yōu)閠oValue。
keyPath內(nèi)容是CALayer的可動(dòng)畫Animatable屬性拢锹。

如果fillMode = kCAFillModeForwards同時(shí)removedOnComletion = NO谣妻，那么在動(dòng)畫執(zhí)行完畢后，圖層會(huì)保持顯示動(dòng)畫執(zhí)行后的狀態(tài)卒稳。但在實(shí)質(zhì)上蹋半，圖層的屬性值還是動(dòng)畫執(zhí)行前的初始值，并沒有真正被改變充坑。
fillMode = kCAFillModeForwards同時(shí)removedOnComletion = NO要同時(shí)設(shè)定才有效

-(void)createCAAnimation
{
    //核心動(dòng)畫是作用在CALayer層的减江，所以先創(chuàng)建一個(gè)layer來承載動(dòng)畫
    CALayer *layer = [[CALayer alloc] init];
    layer.bounds = CGRectMake(0, 0, 100, 100);
    //layer沒有center的屬性，而是position
    layer.position = self.view.center;
    layer.backgroundColor = [[UIColor blackColor]colorWithAlphaComponent:0.5].CGColor;
    [self.view.layer addSublayer:layer];
    
    //創(chuàng)建一個(gè)CAAnimation
    CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];
    //屬性
    //動(dòng)畫持續(xù)的時(shí)間捻爷，默認(rèn)是0 辈灼，    animation.duration = 5;
    //速度比例，默認(rèn)是1也榄，如果調(diào)節(jié)為n茵休，那么在動(dòng)畫持續(xù)時(shí)間內(nèi)會(huì)加速執(zhí)行n次
    animation.speed = 1;
    //開始時(shí)間 ，默認(rèn)是0手蝎，若想延遲ns，就設(shè)置為CACurrentMediaTime()+n俐芯，CACurrentMediaTime()為圖層的當(dāng)前時(shí)間
    animation.beginTime = 0;
    //時(shí)間偏移棵介，用來暫停動(dòng)畫使用
    animation.timeOffset = 0;
    //動(dòng)畫重復(fù)的次數(shù)，默認(rèn)為0吧史，無限循環(huán)可以設(shè)置HUGE_VALF或者M(jìn)AXFLOAT
    animation.repeatCount = 0;
    //動(dòng)畫重復(fù)的時(shí)間間隔邮辽，默認(rèn)0
    animation.repeatDuration = 0;
    //倒向動(dòng)畫，默認(rèn)是NO贸营，如果是Yes,動(dòng)畫正向執(zhí)行后吨述，會(huì)倒向執(zhí)行一次
    animation.autoreverses = NO;
    //默認(rèn)為YES，代表動(dòng)畫執(zhí)行完畢后就從圖層上移除钞脂，圖形會(huì)恢復(fù)到動(dòng)畫執(zhí)行前的狀態(tài)揣云。如果想讓圖層保持顯示動(dòng)畫執(zhí)行后的狀態(tài)，那就設(shè)置為NO冰啃，不過還要設(shè)置fillMode為kCAFillModeForwards
    animation.removedOnCompletion = YES;
    //決定動(dòng)畫開始之前或者結(jié)束之后的形態(tài)
    animation.fillMode = kCAFillModeRemoved;
    //速度控制函數(shù)邓夕，控制動(dòng)畫運(yùn)行的節(jié)奏
    CAMediaTimingFunction *timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
    animation.timingFunction = timingFunction;
    //開始
    animation.fromValue = @(M_PI);
    //結(jié)束
    animation.toValue = @(M_PI/4);
    //為layer加上動(dòng)畫
    [layer addAnimation:animation forKey:@"ANIMATION"];
}

4. CAKeyframeAnimation 關(guān)鍵幀動(dòng)畫

和CABasicAnimation一樣繼承自CAPropertyAnimation刘莹，可以理解為CABasicAnimation的升級(jí)版。

• CABasicAnimation只能指定首尾兩個(gè)keyPath,然后動(dòng)畫從fromValue執(zhí)行到toValue焚刚。
• CAKeyframeAnimation可以指定動(dòng)畫的keypath到一個(gè)values數(shù)組中点弯，然后依次執(zhí)行。

calculationMode

• kCAAnimationLinear//線性，默認(rèn)
• kCAAnimationDiscrete//離散娱节，無中間過程挠蛉，但keyTimes設(shè)置的時(shí)間依舊生效，物體跳躍地出現(xiàn)在各個(gè)關(guān)鍵幀上
• kCAAnimationPaced//平均肄满，keyTimes跟timeFunctions失效
• kCAAnimationCubic//平均谴古，同上
• kCAAnimationCubicPaced//平均，同上

rotationMode

• kCAAnimationRotateAuto
• kCAAnimationRotateAutoReverse

-(void)createValuesAnimation
{
    CAKeyframeAnimation *keyframeAnimation = [CAKeyframeAnimation animationWithKeyPath:@"position"];
    //設(shè)置路徑
    keyframeAnimation.values = [[NSArray alloc] initWithObjects:
                                [NSValue valueWithCGPoint:CGPointMake(self.view.center.x, self.view.center.y)],
                                [NSValue valueWithCGPoint:CGPointMake(self.view.frame.size.width-25, self.view.center.y)],
                                [NSValue valueWithCGPoint:CGPointMake(self.view.frame.size.width-25, self.view.frame.origin.y+89)],
                                [NSValue valueWithCGPoint:CGPointMake(self.view.frame.origin.x+25, self.view.frame.origin.y+89)],
                                [NSValue valueWithCGPoint:CGPointMake(self.view.frame.origin.x+25, self.view.center.y)],
                                 [NSValue valueWithCGPoint:CGPointMake(self.view.frame.origin.x+25, self.view.frame.size.height-25)],
                                [NSValue valueWithCGPoint:CGPointMake(self.view.frame.size.width-25, self.view.frame.size.height-25)],
                                [NSValue valueWithCGPoint:CGPointMake(self.view.center.x, self.view.center.y)],

                                nil];
    //整個(gè)動(dòng)畫的時(shí)長(zhǎng)
    keyframeAnimation.duration = 10;
    //每個(gè)動(dòng)畫的時(shí)長(zhǎng)稠歉，總時(shí)長(zhǎng)為1掰担，然后運(yùn)動(dòng)到那個(gè)點(diǎn)是，該點(diǎn)在總時(shí)長(zhǎng)的百分之幾,和valus個(gè)數(shù)相同
    keyframeAnimation.keyTimes = @[@(0),@(0.2),@(0.4),@(0.5),@(0.55),@(0.7),@(0.9),@(1)];
    keyframeAnimation.repeatCount = MAXFLOAT;
    [self.layer addAnimation:keyframeAnimation forKey:nil];
    [self.view.layer addSublayer:self.layer];

}

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

    //創(chuàng)建一個(gè)路徑
    CGMutablePathRef path = CGPathCreateMutable();
    //添加圓形
    //CGPathAddEllipseInRect(path, NULL, CGRectMake(50, 90, 200, 200));
    //矩形
    CGPathAddRect(path, NULL, CGRectMake(50, 90, 200, 200));

    //設(shè)置路徑
    keyframeAnimation.path = path;

    //釋放路徑
    CGPathRelease(path);
    
    //設(shè)置動(dòng)畫時(shí)間
    keyframeAnimation.duration = 3;
    //原路線返回
    // keyframeAnimation.autoreverses = YES;
      keyframeAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseOut];
    
    //設(shè)置重復(fù)次數(shù)
    keyframeAnimation.repeatCount = MAXFLOAT;
    //勻速kCAAnimationCubicPaced
    keyframeAnimation.calculationMode = kCAAnimationCubicPaced;
    [self.layer addAnimation:keyframeAnimation forKey:nil];
    [self.view.layer addSublayer:self.layer];
}

5.CATransition 轉(zhuǎn)場(chǎng)動(dòng)畫

繼承自CAAnimation,切換頁面的動(dòng)畫怒炸。

subtype的類型

• kCATransitionFromRight 從右邊開始
• kCATransitionFromLeft 從左邊來時(shí)
• kCATransitionFromTop 從上面開始
• kCATransitionFromBottom 從下面開始

- (void)push
{
    //創(chuàng)建一個(gè)轉(zhuǎn)場(chǎng)動(dòng)畫
    CATransition *stansition = [CATransition animation];
    //設(shè)置動(dòng)畫時(shí)間
    stansition.duration = 1;
    //設(shè)置類型
    stansition.type = @"cube";
    stansition.subtype = kCATransitionFromRight;
    //添加動(dòng)畫
    [self.navigationController.view.layer addAnimation:stansition forKey:nil];
    
    NextViewController *nextVC = [[NextViewController alloc] init];
    [self.navigationController pushViewController:nextVC animated:YES]阅羹；  
}

6.CAAnimationGroup 動(dòng)畫組

多個(gè)動(dòng)畫的組合纠炮，即可以把多個(gè)動(dòng)畫放在animations數(shù)組中月趟，然后同時(shí)執(zhí)行多個(gè)動(dòng)畫。

-(void)createAnimationGroup
{
    //創(chuàng)建一個(gè)動(dòng)畫組
    CAAnimationGroup *animationGroup = [[CAAnimationGroup alloc] init];
    //動(dòng)畫時(shí)間恢口，如果動(dòng)畫組中的時(shí)間沒有設(shè)置是不行的孝宗，如果設(shè)置了動(dòng)畫組的時(shí)間，然后里面的動(dòng)畫沒有設(shè)置時(shí)間耕肩， 那么則以動(dòng)畫組的時(shí)間為準(zhǔn)因妇，如果里面的具體動(dòng)畫也設(shè)置了時(shí)間，那么以具體的動(dòng)畫設(shè)置的時(shí)間為準(zhǔn)
    animationGroup.duration = 10;
    //創(chuàng)建一個(gè)基礎(chǔ)動(dòng)畫
    CABasicAnimation *basicAnimaiton = [CABasicAnimation animationWithKeyPath:@"transform.rotation.x"];
    basicAnimaiton.toValue = @(M_PI);
    
    //創(chuàng)建一個(gè)幀動(dòng)畫
    CAKeyframeAnimation *keyframeAnimation = [CAKeyframeAnimation animationWithKeyPath:@"position"];
    //設(shè)置路徑
    keyframeAnimation.values = [[NSArray alloc] initWithObjects:
                                [NSValue valueWithCGPoint:CGPointMake(self.view.center.x, self.view.center.y)],
                                [NSValue valueWithCGPoint:CGPointMake(self.view.frame.size.width-25, self.view.center.y)],
                                [NSValue valueWithCGPoint:CGPointMake(self.view.frame.size.width-25, self.view.frame.origin.y+89)],
                                [NSValue valueWithCGPoint:CGPointMake(self.view.frame.origin.x+25, self.view.frame.origin.y+89)],
                                [NSValue valueWithCGPoint:CGPointMake(self.view.frame.origin.x+25, self.view.center.y)],
                                [NSValue valueWithCGPoint:CGPointMake(self.view.frame.origin.x+25, self.view.frame.size.height-25)],
                                [NSValue valueWithCGPoint:CGPointMake(self.view.frame.size.width-25, self.view.frame.size.height-25)],
                                [NSValue valueWithCGPoint:CGPointMake(self.view.center.x, self.view.center.y)],
                                
                                nil];
    //每個(gè)動(dòng)畫的時(shí)長(zhǎng)猿诸，總時(shí)長(zhǎng)為1婚被，然后運(yùn)動(dòng)到那個(gè)點(diǎn)是，該點(diǎn)在總時(shí)長(zhǎng)的百分之幾,和valus個(gè)數(shù)相同
    keyframeAnimation.keyTimes = @[@(0),@(0.2),@(0.4),@(0.5),@(0.55),@(0.7),@(0.9),@(1)];
    //將兩個(gè)動(dòng)畫添加到動(dòng)畫組中
    animationGroup.animations = @[basicAnimaiton,keyframeAnimation];
    [self.layer addAnimation:animationGroup forKey:nil];
    [self.view.layer addSublayer:self.layer];
}