使用 NSOpenPanel 限制对某些文件夹的访问

Question

我使用 NSOpenPanel 允许用户选择一个文件夹来保存文档。我想限制它们可以保存到哪个文件夹（就层次结构而言）。本质上，我想阻止他们选择上面的任何文件夹：

/用户/用户名/

所以文件夹

/用户/用户名/猫/

是可以接受的，但是

/用户/用户名/

/应用程序/猫/

不允许 。我想知道如何实施这个限制。

谢谢。

Answer 1

请注意 NSOpenPanel 继承自 NSSavePanel，它又定义了委托和相应的委托协议NSOpenSavePanelDelegate。您可以使用委托来扩展打开面板的行为，以便包含您在问题中列出的限制。

例如，假设应用程序委托实现了打开面板限制，请使其符合 NSOpenSavePanelDelegate 协议：

@interface AppDelegate : NSObject <NSApplicationDelegate, NSOpenSavePanelDelegate>
@end

在应用程序委托的实现中，告诉打开面板应用程序委托充当打开面板委托:

NSOpenPanel *openPanel = [NSOpenPanel openPanel];
[openPanel setDirectory:NSHomeDirectory()];
[openPanel setCanChooseDirectories:NO];
[openPanel setDelegate:self];
[openPanel runModal];

并实现以下委托方法：

- (BOOL)panel:(id)sender shouldEnableURL:(NSURL *)url {
    NSString *path = [url path];
    NSString *homeDir = NSHomeDirectory();

    return [path hasPrefix:homeDir] && ! [path isEqualToString:homeDir];
}

- (void)panel:(id)sender didChangeToDirectoryURL:(NSURL *)url {
    NSString *path = [url path];
    NSString *homeDir = NSHomeDirectory();

    // If the user has changed to a non home directory, send him back home!
    if (! [path hasPrefix:homeDir]) [sender setDirectory:homeDir];
}

- (BOOL)panel:(id)sender validateURL:(NSURL *)url error:(NSError **)outError {
    NSString *path = [url path];
    NSString *homeDir = NSHomeDirectory();

    if (![path hasPrefix:homeDir]) {
        if (outError)
           *outError = ; // create an appropriate NSError instance

        return NO;    
    }
    return YES;
}

Answer 2

因此，我尝试将其更新为 Swift 5.5。

我将所有委托方法都包含在内，以便让任何偶然发现此问题的人清楚地了解。

class Utility {
    var homeDirectory: URL?

    func openPanel(url: URL, sender: Any) -> URL? {
        let openPanel = NSOpenPanel()
        openPanel.canChooseDirectories = true
        openPanel.canChooseFiles = false
        openPanel.delegate = self
        appHomeDirectory = url
        openPanel.directoryURL = homeDirectory
        openPanel.showsHiddenFiles = false
        openPanel.canCreateDirectories = true
        switch openPanel.runModal() {
            case .OK:
                print("OK")
            case .cancel:
                print("Cancel")
            case .abort:
                print("Abort")
            case .continue:
                print("Continue")
            case .stop:
                print("Stop")
            default:
                print("Unknown Response")
        }
        return nil
    }

    func panel(_ sender: Any, didChangeToDirectoryURL url: URL?) {
        guard let _url = url else {
            return
        }
        print("didChangeToDirectoryURL")
        print("url: \(_url)")
    }

    func panel(_ sender: Any, shouldEnable url: URL) -> Bool {
        guard let homeDirectory = self.homeDirectory else {
            // Since homeDirectory cannot be set
            return false
        }
        print("shouldEnable")
        print("url path: \(url.path)")
        print("homeDirectory path: \(homeDirectory.path)")
        print("url.path.hasSuffix(homeDirectory.path): \(url.path.hasSuffix(homeDirectory.path))")
        // Removing the last path component of the sent URL
        print("url.deletingLastPathComponent().path.hasSuffix(homeDirectory.path): \(url.deletingLastPathComponent().path.hasSuffix(homeDirectory.path))")
        if url == homeDirectory {
            // This ensures the user can get back into the homeDirectory if
            // they navigated above the homeDirectory.
            return true
        } else {
            // Delete the last path component and then compare if the suffix of the url
            // path is the same as the homeDirectory path and return result.
            return (url.deletingLastPathComponent().path.hasSuffix(homeDirectory.path))
        }
    }

    func panel(_ sender: Any, validate url: URL) throws {
        print("validate")
        print("url: \(url)")
    }

    func panel(_ sender: Any, willExpand expanding: Bool) {
        print("willExpand")
        print("expanding: \(expanding)")
    }

    func panelSelectionDidChange(_ sender: Any?) {
        print("panelSelectionDidChange")
    }

}

在我的 ViewController 中，我有一个“Utility”实例作为“utility”，还有一个 imageButton 的 IBAction，其 Storyboard 标识为“fileBrowseImageButton”。

用法：

@IBAction func fileBrowseImageButtonClicked(sender: Any?) {
    guard let url = utility.openPanel(url: url, sender: sender as! NSButton) else {
        return
    }
    // Do whatever needed with the returned url.
}