Swift: ウィンドウのヒエラルキーを見る

struct Window {
    let ownerName: String
    let name: String
    let windowLayer: Int32

    var description: String {
        return "Owner Name: \(ownerName), Name: \(name), Layer: \(windowLayer)"
    }
}

func checkWindowHierarchy() {
    let windowOptions: CGWindowListOption = [
        .optionOnScreenOnly,
        .optionOnScreenBelowWindow,
        .excludeDesktopElements,
    ]
    guard let windowList = CGWindowListCopyWindowInfo(windowOptions, CGWindowID(0)),
          let array = windowList as NSArray?,
          let dictArray = array as? [[String: AnyObject]]
    else { return }
    let windows = dictArray.compactMap { (item) -> Window? in
        guard let ownerName = item[kCGWindowOwnerName as String] as? String,
              let name = item[kCGWindowName as String] as? String,
              let windowLayer = item[kCGWindowLayer as String] as? Int32
        else { return nil }
        return Window(ownerName: ownerName, name: name, windowLayer: windowLayer)
    }
    .filter { $0.windowLayer == CGWindowLevelKey.baseWindow.rawValue }
    windows.forEach { (window) in
        print(window.description)
    }
}