Method swapChildrenAt

packages/fairygui/src/core/GComponent.ts:327–333

* Swap children at positions * 交换指定位置的子对象

(index1: number, index2: number)

     * 交换指定位置的子对象
     */
    public swapChildrenAt(index1: number, index2: number): void {
        const child1 = this._children[index1];
        const child2 = this._children[index2];

        this.setChildIndex(child1, index2);
        this.setChildIndex(child2, index1);
    }

    /**
     * Check if contains a child