在QLPreviewController中隐藏右侧缩略图栏

Question

当我将QLPreviewController添加为childviewcontroller时，我无法隐藏正确的缩略图栏。我正在使用以下代码：

#import <QuickLook/QuickLook.h>

-(void)viewDidLoad
{
   if ([QLPreviewController canPreviewItem:[[NSBundle mainBundle] URLForResource:@"myFile" withExtension:@"pdf"]])
    {
        QLPreviewController *previewController = [[QLPreviewController alloc] init];
        previewController.dataSource = self;

        [self addChildViewController:previewController];
        [viewQuickLook addSubview:previewController.view];
        [previewController didMoveToParentViewController:self];
    }
}


-(NSInteger) numberOfPreviewItemsInPreviewController:(QLPreviewController *)controller
{
    return 1;
}

- (id <QLPreviewItem>)previewController:(QLPreviewController *)controller previewItemAtIndex:(NSInteger)index
{
    NSURL *pdfURL = [[NSBundle mainBundle] URLForResource:@"myFile" withExtension:@"pdf"];
    return pdfURL;
}

当我使用以下代码时，我可以隐藏缩略图栏。

QLPreviewController *previewController = [[QLPreviewController alloc] init];
previewController.dataSource = self;
[self presentViewController:previewController animated:YES completion:nil];

但我不想要QLPreviewController的导航栏。