gistfile1.swift

func logViewHierarchy(view: UIView) -> String {
    var viewsPrinted = Set<UIView>()
    var result: String = ""

    func printViews(_ view: UIView, level: Int) {
        guard !viewsPrinted.contains(view) else { return }

        let padString = String(repeating: "   | ", count: level)
        result += ("\(padString) \(type(of: view))\n")
        viewsPrinted.insert(view)

        for subview in view.subviews {
            printViews(subview, level: level + 1)
        }
    }
    
    printViews(view, level: 0)

    return result
}

let v = UIView()
for i in 0...10 {
    let view = UIView()

    if i % 2 == 0 {
        view.addSubview(UIView())
    }

    v.addSubview(view)
}

let result = logViewHierarchy(view: v)
print(result)