face-detect这个示例存在的问题

[julyL]

执行以下代码，ios手机中，仍然在使用摄像头

        if (this._texture) {
          this._texture.dispose();
          this._texture = null;
        }
        if (this.renderer) {
          this.renderer.dispose();
          this.renderer = null;
        }
        if (this.scene) {
          this.scene.dispose();
          this.scene = null;
        }
        if (this.camera) this.camera = null;
        if (this.model) this.model = null;
        if (this._insertModel) this._insertModel = null;
        if (this._insertModels) this._insertModels = null;
        if (this.planeBox) this.planeBox = null;
        if (this.mixers) {
          this.mixers.forEach((mixer) => mixer.uncacheRoot(mixer.getRoot()));
          this.mixers = null;
        }
        if (this.clock) this.clock = null;

        if (this.THREE) this.THREE = null;
        if (this._tempTexture && this._tempTexture.gl) {
          this._tempTexture.gl.deleteTexture(this._tempTexture);
          this._tempTexture = null;
        }
        if (this._fb && this._fb.gl) {
          this._fb.gl.deleteFramebuffer(this._fb);
          this._fb = null;
        }
        if (this._program && this._program.gl) {
          this._program.gl.deleteProgram(this._program);
          this._program = null;
        }
        if (this.canvas) this.canvas = null;
        if (this.gl) this.gl = null;
        if (this.session) {
          this.session.destroy();
          console.log('session destroyed');
          this.session = null;
        }
        if (this.anchor2DList) this.anchor2DList = [];