self.view.window.rootViewController.modalPresentationStyle = UIModalPresentationCurrentContext;//半透明
  CocoaPickerViewController *transparentView = [[CocoaPickerViewController alloc] init];
  transparentView.delegate = self;
  transparentView.modalPresentationStyle = UIModalPresentationOverFullScreen;
  transparentView.view.frame=self.view.frame;
  transparentView.view.superview.backgroundColor = [UIColor clearColor];
  [self presentViewController:transparentView animated:YES completion:nil];