How can I set a VC as Liveview in Playgrounds?

Question

I'm currently working on a small Playgrounds project (for macOS) and I'm trying to set my own View Controller as the Live View. The following line doesn't work.

PlaygroundPage.current.liveView = ViewController()

When running this, I get the following error.

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

I get the same error, when using this:

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

Answer 1

Choose File > New > Playground and start with the MacOS Playground template called Single View. This will give you a view in a nib.

Now modify the code in the playground as follows:

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 { $0 is NSView }

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

Run the playground and look in the Assistant Editor pane. You will see this:

---

EDIT It occurs to me that a more pleasant way to write this (placing the decision as to where to get its view in the hands of the view controller itself) would be as follows:

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 { $0 is NSView }
        self.view = views[0] as! NSView
    }
}
PlaygroundPage.current.liveView = ViewController()