在Swift 3中使用NSUndoManager和.prepare(withInvocationTarget :) [英] Using NSUndoManager and .prepare(withInvocationTarget:) in Swift 3

问题描述

我正在将Xcode 7/Swift 2.2 mac OS X项目迁移到Xcode 8/Swift 3，并且在视图控制器类MyViewController中使用undoManager遇到了问题，该类具有撤消功能.

I am migrating an Xcode 7 / Swift 2.2 mac OS X project to Xcode 8 / Swift 3, and I have run into a problem using undoManager in my view controller class, MyViewController, which has a function undo.

在Xcode 7/Swift 2.2中，此方法运行良好:

In Xcode 7 / Swift 2.2, this worked fine:

undoManager?.prepareWithInvocationTarget(self).undo(data, moreData: moreData)
undoManager?.setActionName("Change Data)

在Xcode 8/Swift 3中，使用

In Xcode 8 / Swift 3, using the recommended pattern from https://developer.apple.com/library/content/documentation/Swift/Conceptual/BuildingCocoaApps/AdoptingCocoaDesignPatterns.html

应更改为:

if let target = undoManager?.prepare(withInvocationTarget: self) as? MyViewController {
    target.undo(data, moreData: moreData)
    undoManager?. setActionName("Change Data")
}

但是，向MyViewController的向下转换始终失败，并且未注册撤消操作.

However, the downcast to MyViewController always fails, and the undo operation is not registered.

我在这里遗漏了明显的东西吗，还是这是一个错误?

Am I missing something obvious here, or is this a bug?

推荐答案

prepareWithInvocationTarget(_:)(或Swift 3中的prepare(withInvocationTarget:))创建一个隐藏的代理对象，Swift 3运行时无法很好地使用它.

prepareWithInvocationTarget(_:)(or prepare(withInvocationTarget:) in Swift 3) creates a hidden proxy object, with which Swift 3 runtime cannot work well.

(您可以将其称为错误，然后发送错误报告.)

(You may call that a bug, and send a bug report.)

要达到目的，您不能使用registerUndo(withTarget:handler:)吗?

To achieve your purpose, can't you use registerUndo(withTarget:handler:)?

undoManager?.registerUndo(withTarget: self) {targetSelf in
    targetSelf.undo(data, moreData: moreData)
}

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