下面是一个示例代码，使用UITapGestureRecognizer和PKToolPicker来实现不使用PKCanvasView的情况下使用PKToolPicker。

import UIKit
import PencilKit

class ViewController: UIViewController {

    let toolPicker = PKToolPicker()

    override func viewDidLoad() {
        super.viewDidLoad()

        toolPicker.addObserver(self, forKeyPath: "selectedTool", options: [], context: nil)
        toolPicker.addObserver(self, forKeyPath: "isVisible", options: [], context: nil)

        // 添加一个手势识别器
        let tapGesture = UITapGestureRecognizer(target: self, action: #selector(handleTapGesture(_:)))
        view.addGestureRecognizer(tapGesture)
    }

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)

        // 设置toolPicker的相关属性
        toolPicker.setVisible(true, forFirstResponder: nil)
        toolPicker.addObserver(view, forKeyPath: "color", options: [], context: nil)
        toolPicker.addObserver(view, forKeyPath: "drawingPolicy", options: [], context: nil)
    }

    @objc func handleTapGesture(_ gesture: UITapGestureRecognizer) {
        let location = gesture.location(in: view)

        if toolPicker.frame.contains(location) {
            // 在toolPicker内部点击事件的处理
            return
        }

        // 在toolPicker外部点击事件的处理
        if toolPicker.isVisible {
            toolPicker.setVisible(false, forFirstResponder: nil)
        } else {
            toolPicker.setVisible(true, forFirstResponder: nil)
        }
    }

    // 监听toolPicker的属性变化
    override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
        if keyPath == "selectedTool" {
            if let tool = toolPicker.selectedTool as? PKInkingTool {
                // 处理选中的工具变化
                print("Selected tool: \(tool)")
            }
        } else if keyPath == "isVisible" {
            if toolPicker.isVisible {
                // toolPicker显示
                print("Tool picker is visible")
            } else {
                // toolPicker隐藏
                print("Tool picker is hidden")
            }
        } else if keyPath == "color" {
            if let color = toolPicker.color {
                // 处理颜色变化
                print("Selected color: \(color)")
            }
        } else if keyPath == "drawingPolicy" {
            if let drawingPolicy = toolPicker.drawingPolicy {
                // 处理绘制策略变化
                print("Drawing policy: \(drawingPolicy)")
            }
        }
    }

    deinit {
        toolPicker.removeObserver(self, forKeyPath: "selectedTool")
        toolPicker.removeObserver(self, forKeyPath: "isVisible")
        toolPicker.removeObserver(view, forKeyPath: "color")
        toolPicker.removeObserver(view, forKeyPath: "drawingPolicy")
    }

}

这个示例代码创建了一个UIViewController，并在其中使用了一个UITapGestureRecognizer来监听手势事件。当点击toolPicker内部时，会处理相关的事件，否则会显示或隐藏toolPicker。通过观察toolPicker的选中工具、可见性、颜色和绘制策略等属性的变化，可以实现对这些属性的处理。