Objective c UIDocumentInteractionController与presentOpenInMenuFromBarButtonItem的崩溃：方法

我试图用“openin”菜单打开一个pdf文件，但是当我创建它时，当我调用presentOpenInMenuFromBarButtonItem方法时，代码崩溃了

UIDocumentInteractionController * controller;
        controller = [UIDocumentInteractionController interactionControllerWithURL:fileUrl];
        controller.delegate = self;

        [controller presentOpenInMenuFromBarButtonItem:_openInBBItem animated:YES];

没有错误消息

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你能帮我吗？

解决方案是在UIDocumentInteractionController上保留一个引用

h

m

@property UIDocumentInteractionController* interact;

_interact = [UIDocumentInteractionController interactionControllerWithURL: fileUrl];
_interact.delegate = self;
[_interact presentOpenInMenuFromBarButtonItem: _openInBBItem animated:YES];