抽屉打开，中间视图部分有黑色半透明遮盖层？怎么实现？

[wenyanzhou]

MMDrawerController 实现左边侧滑出界面的时候，center VC 那部分需要 有一层 半透明灰色 遮盖，怎么整？

[subvin]

我这边自己在 centerVC 加了一个遮罩，由dramerController setDrawerVisualStateBlock 回调的 percentVisible 进行控制遮罩的透明度，效果还不错。
[_drawerController setDrawerVisualStateBlock:^(MMDrawerController *drawerController, MMDrawerSide drawerSide, CGFloat percentVisible) {
MMDrawerControllerDrawerVisualState`Block block;
block = [[MMExampleDrawerVisualStateManager sharedManager]
drawerVisualStateBlockForDrawerSide:drawerSide];
if(block){

         block(drawerController, drawerSide, percentVisible);
     }
 }];

[zyj179638121]

[self.drawer setDrawerVisualStateBlock:^(MMDrawerController *drawerController, MMDrawerSide drawerSide, CGFloat percentVisible) {
MMDrawerControllerDrawerVisualStateBlock block;
block = [[MMExampleDrawerVisualStateManager sharedManager]
drawerVisualStateBlockForDrawerSide:drawerSide];
if(block){
block(drawerController, drawerSide, percentVisible);
}

    if (drawerController.openSide == MMDrawerSideNone && percentVisible == 1) {
        drawerController.centerViewController.view.alpha = 0.7;
        drawerController.centerViewController.navigationController.navigationBar.alpha = 0.7;
    }
    
    if (drawerController.openSide == MMDrawerSideLeft && percentVisible == 0) {
        drawerController.centerViewController.view.alpha = 1;
        drawerController.centerViewController.navigationController.navigationBar.alpha = 1;
    }
    
}];