斯威夫特：记录触摸力，大小，持续时间

Question

对于数据分析项目，我想在一个简单的应用程序的日志文件中跟踪触摸力，大小和持续时间的测量值（我使用Apple文档网站上的Foodtracker app）。

我知道我可以从UITouch获得force，size和duration。但

1. 如何访问UITouch进行这些测量？
2. 以及如何将这些测量值写入日志文件？

Answer 1

1. How do I access UITouch to get these measurements?

您必须覆盖视图控制器中的触摸处理程序。

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    super.touchesBegan(touches, with: event)
    let touch = touches.first!
    print("\(touch.force)")
    print("\(touch.majorRadius)")
    print("\(touch.timestamp)")
}

override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
    super.touchesMoved(touches, with: event)
    let touch = touches.first!
    print("\(touch.force)")
    print("\(touch.majorRadius)")
    print("\(touch.timestamp)")
}

override func touchesCancelled(_ touches: Set<UITouch>, with event: UIEvent?) {
    super.touchesCancelled(touches, with: event)
    let touch = touches.first!
    print("\(touch.force)")
    print("\(touch.majorRadius)")
    print("\(touch.timestamp)")
}

2. How do I write these measurements into a log-file?

对于那个结帐这篇文章：Read and write a String from text file