如何在 Playgrounds 中将 VC 设为实时取景？

Question

我目前正在开发一个小型 Playgrounds 项目（适用于 macOS），我正在尝试将自己的视图控制器设置为实时视图。以下行不起作用。

PlaygroundPage.current.liveView = ViewController()

当运行这个时，我得到以下错误。

error: Execution was interrupted, reason: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0).

我得到同样的错误，当使用这个时：

PlaygroundPage.current.liveView = ViewController(nibName: NSNib.Name("MyView"), bundle: Bundle.main)

Answer 1

您可能希望包括以下内容：

PlaygroundPage.current.liveView = ViewController()
PlaygroundPage.current.needsIndefiniteExecution = true

我将 link 附加到类似的问题：How to setup ViewController in Playgrounds? 让我知道是否有帮助！

Answer 2

你的错误是因为你的ViewController()没有任何观点。这里的 link 到 documentation.

If you pass in a nil for nibNameOrNil then nibName will return nil and loadView will throw an exception; in this case you must invoke setView: before view is invoked, or override loadView.

一个可能的修复：

let myVC = NSViewController()
myVC.view = NSView()

PlaygroundPage.current.liveView = myVC

在第二种情况下，您是否像 documentation 所说的那样将 NIB 的文件所有者设置为当前视图控制器？

The specified nib file should typically have the class of the file's owner set to NSViewController, or a custom subclass, with the view outlet connected to a view.

Answer 3

选择“文件”>“新建”>“游乐场”，然后从名为“单一视图”的 MacOS 游乐场模板开始。这将为您提供笔尖视图。

现修改playground中的代码如下：

import AppKit
import PlaygroundSupport

class ViewController : NSViewController {}

let nibFile = NSNib.Name("MyView")
var topLevelObjects : NSArray?

Bundle.main.loadNibNamed(nibFile, owner:nil, topLevelObjects: &topLevelObjects)
let views = (topLevelObjects as! Array<Any>).filter { [=10=] is NSView }

let vc = ViewController()
vc.view = views[0] as! NSView
PlaygroundPage.current.liveView = vc

运行游乐场，然后查看“助理编辑器”窗格。你会看到这个：

编辑我想到一个更愉快的方式来写这个（将决定从哪里获得它的视图在视图控制器本身的手中）是如下：

class ViewController : NSViewController {
    override func loadView() {
        let nibFile = NSNib.Name("MyView")
        var topLevelObjects : NSArray?
        Bundle.main.loadNibNamed(
            nibFile, owner:nil, topLevelObjects: &topLevelObjects)
        let views = (topLevelObjects as! Array<Any>).filter { [=11=] is NSView }
        self.view = views[0] as! NSView
    }
}
PlaygroundPage.current.liveView = ViewController()

如何在 Playgrounds 中将 VC 设为实时取景？

How can I set a VC as Liveview in Playgrounds?

macos

cocoa

swift

swift-playground