關于 Core Animation

Core Animation是一組非常強大的動畫處理API,使用它能做出很多優雅的動畫效果。能用的動畫類有4個子類：CABasicAnimation、CAKeyframeAnimation、CATransition、CAAnimationGroup

開發步驟:

1. 初始化一個動畫對象(CAAnimation)并設置一些動畫相關屬性.

2. 添加動畫對象到層(CALayer)中,開始執行動畫.

CALayer中很多屬性都可以通過CAAnimation實現動畫效果, 包括opacity, position, transform, bounds, contents等，具體可以在API文檔中查找

通過調用CALayer的addAnimation:forKey:增加動畫到層(CALayer)中,這樣就能觸發動畫了.通過調用removeAnimationForKey:可以停止層中的動畫.

注：Core Animation的動畫執行過程都是在后臺操作的,不會阻塞主線程.

創建動畫時你可能用到的屬性

巧妙的運用這些可以屬性實現很棒的動畫效果，比如下面：用CABasicAnimation實現的動畫

CABasicAnimation動畫

簡單的呼吸和搖擺動畫

animation.gif

簡單的代碼

 1.呼吸動畫
    CABasicAnimation *animation =[CABasicAnimation animationWithKeyPath:@"opacity"];
    animation.fromValue = [NSNumber numberWithFloat:1.0f];
    animation.toValue = [NSNumber numberWithFloat:0.0f];
    animation.autoreverses = YES;    //回退動畫（動畫可逆，即循環）
    animation.duration = 1.0f;
    animation.repeatCount = MAXFLOAT;
    animation.removedOnCompletion = NO;
    animation.fillMode = kCAFillModeForwards;//removedOnCompletion,fillMode配合使用保持動畫完成效果
    animation.timingFunction=[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn];
    [self.alphaTagButton.layer addAnimation:animation forKey:@"aAlpha"];  

2.搖擺動畫
    //設置旋轉原點
    self.sharkTagButton.layer.anchorPoint = CGPointMake(0.5, 0);
    CABasicAnimation* rotationAnimation = [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];
    //角度轉弧度（這里用1，-1簡單處理一下）
    rotationAnimation.toValue = [NSNumber numberWithFloat:1];
    rotationAnimation.fromValue = [NSNumber numberWithFloat:-1];
    rotationAnimation.duration = 1.0f;
    rotationAnimation.repeatCount = MAXFLOAT;
    rotationAnimation.removedOnCompletion = NO;
    rotationAnimation.autoreverses = YES;
    rotationAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
    rotationAnimation.fillMode = kCAFillModeForwards;
    [self.sharkTagButton.layer addAnimation:rotationAnimation forKey:@"revItUpAnimation"];

陀螺儀&加速儀的動畫

ps:好吧 這個屬于亂入，和上面的搖擺動畫差不多的效果，只是這個是手動的 哈哈

3、陀螺儀&加速儀的動畫
    self.motionManager = [[CMMotionManager alloc] init];
    self.motionManager.deviceMotionUpdateInterval = 1.0f/100.0f; //1秒100次
    self.sharkTagButton.layer.anchorPoint = CGPointMake(0.5, 0);
    [self.motionManager startDeviceMotionUpdatesToQueue:[NSOperationQueue currentQueue] withHandler:^(CMDeviceMotion *motion, NSError *error) {
        if(fabs(motion.attitude.roll)<1.0f)
        {
            [UIView animateWithDuration:0.6 animations:^{
                self.sharkTagButton.layer.transform = CATransform3DMakeRotation(-(motion.attitude.roll), 0, 0, 1);
            }];
        }else if (fabs(motion.attitude.roll)<1.5f)
        {
            [UIView animateWithDuration:0.6 animations:^{
                int s;
                if (motion.attitude.roll>0)
                {
                    s=-1;
                }else
                {
                    s = 1;
                }
                self.sharkTagButton.layer.transform = CATransform3DMakeRotation(s*M_PI_2, 0, 0, 1);
            }];
        }
        if ((motion.attitude.pitch)<0)
        {
            [UIView animateWithDuration:0.6 animations:^{
                self.sharkTagButton.layer.transform = CATransform3DMakeRotation(M_PI, 0, 0, 1);
            }];
        }

    }];

Demo地址：
https://github.com/yongliangP/CABasicAnimationDemo

CATransition之簡單的轉場動畫

CAAnimation的子類，用于做轉場動畫，能夠為層提供移出屏幕和移入屏幕的動畫效果。

• 常用動畫類型:

注：私有API只能通過字符串使用哈

• 過渡方向參數:

簡單的CATransition動畫

CATransitionDemo2.gif

-(void)animationWithType:(NSString*)type
{

    //- 創建一個轉場動畫:
    CATransition *transition = [CATransition animation];
    transition.repeatCount = 5;

    //    - 確定動畫類型:
    transition.type = type;

    //    - 確定子類型(方向等)
    transition.subtype = kCATransitionFromLeft;

    //    - 確定動畫時間
    transition.duration = 1;

    //    - 添加動畫
    [self.imageView.layer addAnimation:transition forKey:nil];

}

使用時只用傳你的想要的動畫類型就好，私有API只能通過字符串使用哈。

[self animationWithType:self.dataArray[indexPath.row]];

DEMO地址：https://github.com/yongliangP/CATransitionDemo

---20160908更新

CAKeyframeAnimation

先看圖，就是那個在跑的小圓球，為了方便，把動畫集成在了一個Demo里了

ScreenShotDemo2.gif

• 1 .簡單介紹

  CAKeyframeAnimation是CApropertyAnimation的子類，跟CABasicAnimation的區別是：CABasicAnimation只能從一個數值(fromValue)變到另一個數值(toValue)，而CAKeyframeAnimation會使用一個NSArray保存這些數值，是一種更靈活的動畫方式。

• 2 .屬性介紹

• 3 .實現
  • 3.1 values方式實現

-(void)setUpCAKeyframeAnimationUseValues
{

    CAKeyframeAnimation *animation = [CAKeyframeAnimation animation];

    animation.keyPath = @"position";

    NSValue *value1 = [NSValue valueWithCGPoint:CGPointMake(50, 50)];

    NSValue *value2 = [NSValue valueWithCGPoint:CGPointMake(kWindowWidth - 50, 50)];

    NSValue *value3 = [NSValue valueWithCGPoint:CGPointMake(kWindowWidth - 50, kWindowHeight-50)];

    NSValue *value4 = [NSValue valueWithCGPoint:CGPointMake(50, kWindowHeight-50)];

    NSValue *value5 = [NSValue valueWithCGPoint:CGPointMake(50, 50)];

    animation.values = @[value1,value2,value3,value4,value5];
    animation.repeatCount = MAXFLOAT;

    animation.removedOnCompletion = NO;

    animation.fillMode = kCAFillModeForwards;

    animation.duration = 6.0f;

    animation.timingFunction=[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];

    [self.keyButton.layer addAnimation:animation forKey:@"values"];

}

• • 3.2 path方式實現

-(void)setUpCAKeyframeAnimationUsePath
{
    CAKeyframeAnimation *animation = [CAKeyframeAnimation animation];

    animation.keyPath = @"position";

    CGMutablePathRef path = CGPathCreateMutable();

    //矩形線路
    CGPathAddRect(path, NULL, CGRectMake(50,50, kWindowWidth - 100,kWindowHeight - 100));

    animation.path=path;

    CGPathRelease(path);

    animation.repeatCount = MAXFLOAT;

    animation.removedOnCompletion = NO;

    animation.fillMode = kCAFillModeForwards;

    animation.duration = 10.0f;

    animation.timingFunction=[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];

    [self.keyButton.layer addAnimation:animation forKey:@"path"];


}

• • 3.3 keyTimes演示

-(void)setUpCAKeyframeAnimationUsekeyTimes
{

    CAKeyframeAnimation *animation = [CAKeyframeAnimation animation];
//    animation.keyPath = @"transform.translation.x";
    animation.keyPath = @"position.x";
    animation.values = @[@0, @20, @-20, @20, @0];
    animation.keyTimes = @[ @0, @(1 / 6.0), @(3 / 6.0), @(5 / 6.0), @1 ];
    animation.duration = 0.5;
    animation.additive = YES;
    [self.sharkTagButton.layer addAnimation:animation forKey:@"keyTimes"];

}

---20160921更新

CAAnimationGroup

看圖，就是那個下方的小長方形，簡單實現

ScreenShotGroupDemo.gif

動畫組，顧名思義就是動畫的組合，具體動畫可以參考上文，不同的腦洞會出現不同的化學反應。

簡單示例：

    CABasicAnimation * animationScale = [CABasicAnimation animation];
    animationScale.keyPath = @"transform.scale";
    animationScale.toValue = @(0.1);

    CABasicAnimation *animationRota = [CABasicAnimation animation];
    animationRota.keyPath = @"transform.rotation";
    animationRota.toValue = @(M_PI_2);

    CAAnimationGroup * group = [[CAAnimationGroup alloc] init];
    group.duration = 3.0;
    group.fillMode = kCAFillModeForwards;
    group.removedOnCompletion = NO;
    group.repeatCount = MAXFLOAT;

    group.animations = @[animationScale,animationRota];
    [self.groupButton.layer addAnimation:group forKey:nil];

Demo傳送門

附：關于keyPath你可能用到的屬性

照例放Demo
Demo地址：
https://github.com/yongliangP/CABasicAnimationDemo