带标识符的NSTableView单元格保持零 [英] NSTableView Cell with Identifier keep giving nil

问题描述

我正在构建MacOS应用程序.我试图使当我按下添加按钮时更新单元格的表视图.

I am working on building MacOS app. I am trying to make table view that updates the cell when I press add button.

以下是我的代码:

 func tableView(_ tableView: NSTableView, viewFor tableColumn: NSTableColumn?, row: Int) -> NSView? {
    let identifier = tableColumn?.identifier as NSString?
    if ( identifier == "NameCell")
    {
        var result: NSTableCellView
        let cell = tableView.make(withIdentifier: "NameCell", owner: self) as! NSTableCellView
        cell.textField?.stringValue = self.data[row].setting!
            return cell

    }
    else if (identifier == "SettingCell")
    {
        if let cell = tableView.make(withIdentifier: "SettingCell", owner: self) as? NSTableCellView {
        cell.textField?.stringValue = self.data[row].setting!
        return cell
    }
    }
    return nil
}

但是，这一行让cell = tableView.make(withIdentifier:"NameCell"，owner:self)为！ NSTableCellView不断失败，因为它返回nil

However, the line let cell = tableView.make(withIdentifier: "NameCell", owner: self) as! NSTableCellView is keep failing because it returns nil

致命错误:解开可选值时意外发现nil

fatal error: unexpectedly found nil while unwrapping an Optional value

NameCell来自 谁能帮我找到解决这个问题的方法吗?

NameCell is from Can anyone please help me find a way to solve this problem?

推荐答案

对于尝试完全以编程方式制作NSTableView时遇到相同问题的其他人:

For anyone else who comes here with this same question when trying to make an NSTableView fully programmatically: makeView(withIdentifier:owner:) WILL return nil unless a corresponding NIB exists for the given identifier:

NSTableView文档:

NSTableView documentation:

如果无法从nib文件实例化或在重用队列中找到具有指定标识符的视图，则此方法返回nil.

If a view with the specified identifier can’t be instantiated from the nib file or found in the reuse queue, this method returns nil.

同样，所有者"参数是NIB特定的概念.简而言之:如果以编程方式用单元格填充NSTableView，则不能使用此方法.

Likewise, the 'owner' param is a NIB-specific concept. In short: you cannot use this method if populating your NSTableView with cells programmatically.

在此答案中，我详细介绍了Swift代码以编程方式生成NSTableCellView: https://stackoverflow.com/a/51736468/5951226

In this answer, I detail the Swift code to produce an NSTableCellView programmatically: https://stackoverflow.com/a/51736468/5951226

但是，如果您不希望NSTableViewCell的所有功能，请注意，您可以在any NSView. com/documentation/appkit/nstableviewdelegate/1527449-tableview"rel =" noreferrer> tableView(_:viewFor:row:) .因此，您可以按照 CocoaProgrammaticHowtoCollection ，只需写:

However, if you don't want all the features of an NSTableViewCell, note that you can return any NSView in tableView(_:viewFor:row:). So you could, as per the CocoaProgrammaticHowtoCollection, simply write:

let cell = NSTextField()
cell.identifier = "my_id" // Essential! Allows re-use of the instance.
// ... Set any properties you want on the NSTextField.
return cell

这篇关于带标识符的NSTableView单元格保持零的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！