在UIDocumentBrowserVC中自动选择UIDocument [英] Pick UIDocument automatically in UIDocumentBrowserVC

问题描述

我正在使用uidocumentbrowservc，并希望以编程方式选择UIDocument.就我而言，这是因为我想自动加载上次使用的UIDocument来节省用户启动时间，因为我的应用很少更改文档.

I am using a uidocumentbrowservc and want to pick a UIDocument programmatically. In my case it is because i want to automatically load the last used UIDocument to save the user some time on launch, as my app seldom changes documents.

我幼稚的方法是将上次使用的URL存储在UserDefaults中.然后在uidocumentbrowservc的viewDidLoad()中调用presentDocument(at: URL).但这是行不通的.当我打电话给URL.checkResourceIsReachable()时，我得到了错误:

My naive approach is to store last used URL in UserDefaults. Then in the viewDidLoad() of my uidocumentbrowservc I call presentDocument(at: URL). But it doesn't work. And when i call URL.checkResourceIsReachable() I get the error:

Error Domain = NSCocoaErrorDomain代码= 257文件"myFile"无法 因为您没有查看权限而被打开."

Error Domain=NSCocoaErrorDomain Code=257 "The file "myFile" couldn’t be opened because you don’t have permission to view it."

文件路径为:

/private/var/mobile/Library/Mobile Documents/com~apple~CloudDocs/MyApp/myFile.

据我了解，我无权访问它，因为它不在我的沙箱中(它可以在用户保存它的任何位置?).

As far as I understand, I don't have access to it because it is not in my sandbox (It could be anywhere the user saves it?).

有什么建议吗?我相信有更好的方法可以做到这一点.

Any suggestions? I am sure there exist better ways to do this.

推荐答案

您不能仅保存URL.您还需要保存UIDBVC授予您的沙盒扩展.保存一个书签而不是URL可以做到这一点.此外，如果用户移动文件(例如，在其他设备上的iCloud Drive内部重命名)，书签将继续起作用.普通网址不会.

You cannot just save the URL. You need to save the sandbox extension granted to you by UIDBVC as well. Saving a bookmark instead of the URL will do that. In addition, a bookmark will keep working if the user moves the file (e.g. renamed inside iCloud Drive on a different device). A plain URL will not.

使用选项.withSecurityScope和URLByResolvingBookmarkData:options:relativeToURL:bookmarkDataIsStale:error:检查URL的bookmarkData(options:includesResourceValuesForKeys:relativeTo:)(然后不要忘记对结果URL调用start/stopAccessing)

Check out URL’s bookmarkData(options:includingResourceValuesForKeys:relativeTo:) with options .withSecurityScope and URLByResolvingBookmarkData:options:relativeToURL:bookmarkDataIsStale:error: (and then don’t forget to call start/stopAccessing on the resulting URL)

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