swift - 尝试预览文件时无法让 QuickLook 工作

Question

我正在使用 Storyboard使用 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。

我似乎一切就绪，我的代码看起来与此处描述的非常相似:QuickLook consumer as a delegate from an NSViewController , 但我不断收到错误

-[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使用 Swift 和 Storyboard的情况调整上述帖子的解决方案。

主要部分是:

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
    }
} 

无论是否干扰响应链，我都会收到错误消息。委托(delegate)函数也都按预期被调用。

Answer 1

移除

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

在 quickLookButtonAction 中，viewcontroller 还没有控制。等待 beginPreviewPanelControl。

来自 currentController 的文档:

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 中对 -beginPreviewPanelControl: 的评论:

Sent to the object taking control of the Preview Panel.

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