尝试预览文件时无法使QuickLook正常工作 [英] Can't get QuickLook to work when trying to preview files

问题描述

我正在使用故事板用Swift编写macOS应用程序.我有一个NSTableView，其中包含我希望用户能够通过QuickLook预览的文件.

I am writing a macOS application with Swift using story boards. I have a NSTableView which contains files that I want the user to be able to preview via QuickLook.

我似乎已准备好所有内容，并且我的代码与此处描述的代码非常相似:

I seemingly have everything in place and my code looks very similar to what has been described here: QuickLook consumer as a delegate from an NSViewController, but I keep getting the error

-[QLPreviewPanel setDataSource:] called while the panel has no controller - Fix this or this will raise soon.
    See comments in QLPreviewPanel.h for -acceptsPreviewPanelControl:/-beginPreviewPanelControl:/-endPreviewPanelControl:.

我一直在尝试根据我在Swift和故事板上的情况来调整以上帖子的解决方案.

I've been trying to adapt the solution of above post to my situation with Swift and story boards.

主要作品是:

import Quartz

class ViewController: NSViewController, QLPreviewPanelDataSource, QLPreviewPanelDelegate {

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
        let windowNextResponder = self.view.window?.nextResponder
        self.view.window?.nextResponder = self
        self.nextResponder = windowNextResponder
    }

    // *** Quicklook stuff ***

    @IBAction func quickLookButtonAction(_ sender: Any) {
        guard qlPanel != nil else {
            return
        }

        if qlPanel!.currentController == nil {
            print ("No controller")
            //qlPanel!.windowController = self.view.window?.windowController
            // qlPanel!.updateController()
        } else {
            print (qlPanel!.currentController)
        }
        qlPanel!.delegate = self
        qlPanel!.dataSource = self

        qlPanel!.makeKeyAndOrderFront(self)
    }

    func numberOfPreviewItems(in panel: QLPreviewPanel!) -> Int {
        return CSVarrayController.selectedObjects.count
    }

    func previewPanel(_ panel: QLPreviewPanel!, previewItemAt index: Int) -> QLPreviewItem! {
        let file = CSVarrayController.selectedObjects[index] as! CSVfile
        return file.url as NSURL
    }
    override func acceptsPreviewPanelControl(_ panel: QLPreviewPanel!) -> Bool {
        return true
    }
    override func beginPreviewPanelControl(_ panel: QLPreviewPanel!) {
        panel.dataSource = self
        panel.delegate = self
    }

    override func endPreviewPanelControl(_ panel: QLPreviewPanel!) {
        panel.dataSource = nil
        panel.delegate = nil
    }
} 

无论响应者链是否混乱，我都会收到错误消息. 委托函数也都按预期被调用.

With or without messing with the responder chain I get the error. The delegate functions all get called as expected as well.

推荐答案

删除

qlPanel!.delegate = self
qlPanel!.dataSource = self

在quickLookButtonAction中的

，该视图控制器尚未处于控制状态.等待beginPreviewPanelControl.

来自currentController的文档:

如果不控制预览面板的状态(其委托，数据源等)，则永远不要更改它.

You should never change the preview panel’s state (its delegate, datasource, and so on) if you are not controlling it.

来自QLPreviewPanel.h中针对-beginPreviewPanelControl:的注释:

From comments in QLPreviewPanel.h for -beginPreviewPanelControl::

发送到控制预览面板的对象.

Sent to the object taking control of the Preview Panel.

接收者应在此处设置预览面板(数据源，委托，绑定等).

The receiver should setup the preview panel (data source, delegate, binding, etc.) here.

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