presentViewController弹出一个半透明的UIViewController

UIViewController 推出另外一个半透明的UIViewController

    UIViewController *controller = [[UIViewController alloc]init];
    if ([[[UIDevice currentDevice] systemVersion] floatValue]>=8.0) {
        nav.modalPresentationStyle=UIModalPresentationOverCurrentContext;
    }else{
        nav.modalPresentationStyle=UIModalPresentationCurrentContext;
    }
    controller.view.backgroundColor = [UIColor colorWithWhite:.0f alpha:.65f];
    [self presentViewController:controller animated:YES completion:nil];