pspdfkit自定义保存iOS

我现在正在使用用于ios的pspdfkit，我现在可以从本地目录为pdf添加注释。问题是注释是自动保存的。我已经像这样打开了pdf。如何仅在按下“保存”按钮时保存pdf？我可以做自定义保存按钮，如以下代码

PSPDFDocument *document = [PSPDFDocument documentWithURL:documentURL];
PSPDFViewController *pdfController = [[PSPDFViewController alloc] initWithDocument:document];

pdfController.openInButtonItem.openOptions = PSPDFOpenInOptionsOriginal;
UIBarButtonItem *backButton = [[UIBarButtonItem alloc] initWithTitle:@"Back" style:UIBarButtonItemStyleBordered target:self action:@selector(backFromDocument)] ;
pdfController.leftBarButtonItems = @[backButton];

pdfController.rightBarButtonItems = @[pdfController.annotationButtonItem, pdfController.searchButtonItem, pdfController.outlineButtonItem, pdfController.viewModeButtonItem];

UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:pdfController];
[self presentViewController:navController animated:YES completion:NULL];

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要禁用自动保存功能，请对PSPDF文档调用

document.annotationSaveMode=PSPDFAnnotationSaveModeDisabled

要通过单击特定按钮保存批注，可以在PSPDAnnotationParser中调用

saveAnnotationsWithError