CAKeyframeAnimation——关键帧动画和动画组~

// 增加一个中间点
    // 中心点用个随机点
    // 1. 动画
    CAKeyframeAnimation *anim = [CAKeyframeAnimation animationWithKeyPath:@"position"];
    
    NSValue *p1 = [NSValue valueWithCGPoint:self.center];
    NSValue *p2 = [NSValue valueWithCGPoint:[self randomPoint]];
    NSValue *p3 = [NSValue valueWithCGPoint:to];
    
    anim.values = @[p1, p2, p3];
    
    anim.duration = 1.0f;
    
    anim.removedOnCompletion = NO;
    anim.fillMode = kCAFillModeForwards;
    
    anim.delegate = self;
    
    [self.layer addAnimation:anim forKey:nil];

- (void)shake
{
    // 1. 动画
    CAKeyframeAnimation *anim = [CAKeyframeAnimation animationWithKeyPath:@"transform.rotation"];
    
    // 2. 设置角度
    CGFloat angle = M_PI_4 / 10;
    
    anim.values = @[@(-angle), @(angle), @(-angle)];
    
    anim.duration = 0.2f;
    anim.repeatCount = HUGE_VALF;
    
    [self.layer addAnimation:anim forKey:nil];
}

#pragma mark - 按照路径平移的关键帧动画
- (CAKeyframeAnimation *)moveWithPath:(CGPathRef)path duration:(NSTimeInterval)duration
{
    // 1. 动画
    CAKeyframeAnimation *anim = [CAKeyframeAnimation animationWithKeyPath:@"position"];
    
    // 2. 设置路径
    anim.path = path;
    
    // 3. 设置时长
    anim.duration = duration;
    
    return anim;
}

- (void)groupDemo
{
    /**
     群组动画可以将一组动画继承在一起，并发执行，产生更加复杂的动画效果
     
     需要注意的是，群组中的动画，不能修改同一个keyPath
     */
    // 实例化一个动画组
    CAAnimationGroup *group = [[CAAnimationGroup alloc] init];
    
    // 透明度动画
    CABasicAnimation *alpha = [CABasicAnimation animationWithKeyPath:@"opacity"];
    
    alpha.fromValue = @(1.0);
    alpha.toValue = @(0.5);
    
    // 旋转动画
    CABasicAnimation *rotate = [CABasicAnimation animationWithKeyPath:@"transform.rotation"];
    
    rotate.toValue = @(2 * M_PI);
    
    // 关键帧动画
    CAKeyframeAnimation *keyAnim = [CAKeyframeAnimation animationWithKeyPath:@"position"];
    
    CGMutablePathRef path = CGPathCreateMutable();
    CGPathAddEllipseInRect(path, NULL, CGRectMake(100, 100, 200, 300));
    
    keyAnim.path = path;
    
    // 释放路径
    CGPathRelease(path);
    
    group.animations = @[alpha, keyAnim, rotate];
    group.duration = 1.0f;
    
    [_myView.layer addAnimation:group forKey:nil];
}