清单8.4 使用KVC对动画打标签 代码有问题

[panzhou]

我仔细看了下代码，按照那里的写法的确能够成功执行。但是我发现

- (void)setAngle:(CGFloat)angle forHand:(UIView *)handView animated:(BOOL)animated
{
    //generate transform
    CATransform3D transform = CATransform3DMakeRotation(angle, 0, 0, 1);
    if (animated) {
        //create transform animation
        CABasicAnimation *animation = [CABasicAnimation animation];
        [self updateHandsAnimated:NO];
        animation.keyPath = @"transform";
        animation.toValue = [NSValue valueWithCATransform3D:transform];
        animation.duration = 0.5;
        animation.delegate = self;
        [animation setValue:handView forKey:@"handView"];
        [handView.layer addAnimation:animation forKey:nil];
    } else {
        //set transform directly
        handView.layer.transform = transform;
    }
}

这段代码里面 修改成

- (void)setAngle:(CGFloat)angle forHand:(UIView *)handView animated:(BOOL)animated
{
    //generate transform
    CATransform3D transform = CATransform3DMakeRotation(angle, 0, 0, 1);
    handView.layer.transform = transform;
}

一样能成功执行，因为以上代码主要的作用只是做了一个transform转换，并没有达到CABasicAnimation的目的。我觉得其实作者想要实现的效果应该是

- (void)setAngle:(CGFloat )angle forHand:(UIImageView *)handView animated:(BOOL)animated
{
    CATransform3D transform = CATransform3DMakeRotation(angle, 0, 0, 1);
    if (animated) {
        CABasicAnimation *animation = [CABasicAnimation animation];
        animation.keyPath = @"transform";
        animation.toValue = [NSValue valueWithCATransform3D:transform];
        animation.duration = 0.5;
        animation.fillMode = kCAFillModeForwards;
        animation.removedOnCompletion = NO;
        [handView.layer addAnimation:animation forKey:nil];
    }
    else
    {
        handView.layer.transform = transform;
    }
}

作者可以参考下