swift - 如何通过函数外的按钮修改函数？

Question

func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {

    let location = locations[0]

    let kmh = String(format: "%.0f",(location.speed*3.6))
    let ms = String(format: "%.0f",(location.speed))

    speedLabel.text = kmh // change [kmh] to [ms] when the button is tapped

当我点击此按钮 (msBtn) 时，我希望函数 (speedLabel.text) 中的速度标签从 kmh 更改到 ms。

@IBAction func msBtn(_ sender: Any) {
    // add some magic code here //
}

Answer 1

在类中创建一个 bool 值并更改它。

var shouldDisplayKmh = true

func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) { 
    let location = locations[0]
    let speed = String(format: "%.0f",(location.speed * (shouldDisplayKmh ? 3.6 : 1)))
    speedLabel.text = speed
}

@IBAction func msBtn(_ sender: Any) {
    shouldDisplayKmh = !shouldDisplayKmh
}