ccc learning step by step

[ccc]cc.tween

start () {

      /**
       //cc.Action 已弃用 

       let action = cc.repeatForever(
          cc.sequence(
              cc.rotateBy(0.3,4),
              cc.rotateBy(0.3,-8),
              cc.rotateBy(0.3,4),
              cc.delayTime(0.5)
          )
      );

      this.startBtn.runAction(action);
       */

       //新方法 tween https://docs.cocos.com/creator/api/zh/classes/Tween.html?h=tween
      cc.tween(this.startBtn)
      .repeatForever(
          cc.sequence(
              cc.rotateBy(0.3,4),
              cc.rotateBy(0.3,-8),
              cc.rotateBy(0.3,4),
              cc.delayTime(0.5)
          )
      ).start();

  }

cc.tween有两种主要的设置方式：
to 改变到某个值
by 变化值