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.

如果为nbNameOrNil传递nil，则nibName将返回nil，并且loadView会引发异常；在这种情况下，您必须在调用视图之前调用setView：，或重写loadView。

 -[NSNib _initWithNibNamed:bundle:options:] could not load the nibName: CodeCreateUiDemo.JFProgrammaticallyViewController in bundle (null).

import Cocoa
import SnapKitclass ViewController: NSViewController {var button : NSButton!override func viewDidLoad() {super.viewDidLoad()button = NSButton(frame: CGRect(x: 0, y: 0, width: 100, height: 100))button.wantsLayer = truebutton.layer?.backgroundColor = NSColor.red.cgColorbutton.title = "click"button.target = selfbutton.action = #selector(clickAction(sender:))self.view.addSubview(button)}@objc func clickAction(sender:NSButton) {let programmaticallyVC = JFProgrammaticallyViewController()self.presentAsModalWindow(programmaticallyVC)}override var representedObject: Any? {didSet {// Update the view, if already loaded.}}}//纯代码创建的ViewController
import Cocoaclass JFProgrammaticallyViewController: NSViewController {var mView : NSView!//这一端是重重之中，对于无法通过Nib加载view，就要通过loadView()方法来进行补救，override func loadView() {self.view = NSView(frame: CGRect(x: 0, y: 0, width: 400, height: 300))}override func viewDidLoad() {super.viewDidLoad()mView = NSView(frame: NSRect(x: 0, y: 0, width: self.view.bounds.size.width, height: self.view.bounds.size.height))mView.wantsLayer = truemView.layer?.backgroundColor = NSColor.red.cgColorself.view.addSubview(mView)}}