SKSpriteNode 旋转无法正常工作

Question

我正在尝试使用 UIRrotationGestureRecognizer 旋转 SKSpriteNode。我已经实现了一个代码，但有时，当我旋转节点时，它会跳转到一个不应该的旋转。这里有代码：

- (void) handleRotation:(UIRotationGestureRecognizer *) rotationrecognizer{

    CGFloat initialrotation = 0.0;

    if (rotationrecognizer.state == UIGestureRecognizerStateBegan) {

      CGPoint touchLocation = [rotationrecognizer locationInView:rotationrecognizer.view];
      touchLocation = [self convertPointFromView:touchLocation];
      [self selectNodeForTouch:touchLocation];

      initialrotation = selected.zRotation;
    }

    else if (rotationrecognizer.state == UIGestureRecognizerStateChanged) {        

      CGFloat angle = initialrotation + rotationrecognizer.rotation;
      selected.zRotation = angle;      

   }   
}

Answer 1

您在每次调用时将初始轮换重置为 0...如果您需要它保持驻留，您应该将其移动为您的视图的 ivar。

按照你现在写的方式，设置“角度”的那行实际上等于：

CGFloat angle = 0 + rotationrecognizer.rotation;

相反，您应该执行以下操作（其中 initialRotation 被定义为私有 ivar）：

- (void) handleRotation:(UIRotationGestureRecognizer *) rotationrecognizer{

    if (rotationrecognizer.state == UIGestureRecognizerStateBegan) {

      CGPoint touchLocation = [rotationrecognizer locationInView:rotationrecognizer.view];
      touchLocation = [self convertPointFromView:touchLocation];
      [self selectNodeForTouch:touchLocation];

      _initialrotation = selected.zRotation;
    }

    else if (rotationrecognizer.state == UIGestureRecognizerStateChanged) {        

      CGFloat angle = _initialrotation + rotationrecognizer.rotation;
      selected.zRotation = angle;      

   }   
}