形状层的动画路径

我为自己认为的简单问题感到困惑。

我想绘制由线连接的视图，为视图的位置设置动画，并使连接线也为动画。我创建视图，并在它们之间创建一条线，如下所示：

- (UIBezierPath *)pathFrom:(CGPoint)pointA to:(CGPoint)pointB {
    CGFloat halfY = pointA.y + 0.5*(pointB.y - pointA.y);
    UIBezierPath *linePath=[UIBezierPath bezierPath];
    [linePath moveToPoint: pointA];
    [linePath addLineToPoint:CGPointMake(pointA.x, halfY)];
    [linePath addLineToPoint:CGPointMake(pointB.x, halfY)];
    [linePath addLineToPoint:pointB];
    return linePath;
}

-(void)makeTheLine {
    CGPoint pointA = self.viewA.center;
    CGPoint pointB = self.viewB.center;

    CAShapeLayer *lineShape = [CAShapeLayer layer];
    UIBezierPath *linePath=[self pathFrom:pointA to:pointB];
    lineShape.path=linePath.CGPath;

    lineShape.fillColor = nil;
    lineShape.opacity = 1.0;
    lineShape.strokeColor = [UIColor blackColor].CGColor;
    [self.view.layer addSublayer:lineShape];
    self.lineShape = lineShape;
}

它画出了我想要的样子。我从文档中了解到，可以通过在动画块中更改形状来对形状的路径进行动画处理，如下所示：

- (void)moveViewATo:(CGPoint)dest {
    UIBezierPath *destPath=[self pathFrom:dest to:self.viewB.center];
    [UIView animateWithDuration:1 animations:^{
        self.viewA.center = dest;
        self.lineShape.path = destPath.CGPath;
    }];
}

但是没有骰子。视图位置会按预期进行动画处理，但是连接到另一个视图的线会“跳转”到目标路径。

这个答案意味着我在做什么应该起作用。而这个答案意味着一个CABasic动画，因为这似乎更糟糕，我（一个），那么我需要做同向视图冷得多块动画协调，和（b）当我试图这样，线没”根本没有改变...

// worse way
- (void)moveViewATo:(CGPoint)dest {
    UIBezierPath *linePath=[self pathFrom:dest to:self.viewB.center];
    [UIView animateWithDuration:1 animations:^{
        self.viewA.center = dest;
        //self.lineShape.path = linePath.CGPath;
    }];

    CABasicAnimation *morph = [CABasicAnimation animationWithKeyPath:@"path"];
    morph.duration = 1;
    morph.toValue = (id)linePath.CGPath;
    [self.view.layer addAnimation:morph forKey:nil];
}

提前致谢。