list的add跟remove item的入场、出场动画

  @State 
  transitionTime: TransitionEffect = (TransitionEffect.IDENTITY) 
  
  setDeleteAnimation() { 
    this.transitionTime = (TransitionEffect.opacity(0) 
      .animation({ 
        duration: 300, 
      })).combine(TransitionEffect.asymmetric(TransitionEffect.move(TransitionEdge.END), 
      TransitionEffect.move(TransitionEdge.START))) 
  } 
  
  setAddAnimation() { 
    this.transitionTime = (TransitionEffect.opacity(0) 
      .animation({ 
        duration: 300, 
        delay:500 
      })).combine(TransitionEffect.asymmetric(TransitionEffect.move(TransitionEdge.END), 
      TransitionEffect.move(TransitionEdge.START))) 
  }