ios - Core Motion 将距离转换为 KM

Question

在我的健康应用程序中，它显示距离 0.1 公里，但在我的应用程序中，它给我的值为 0.106。我怎样才能将其更改为 1 小数？这是我用来获取当前统计数据的代码:

pedometer.queryPedometerData(from: Date().startOfDay, to: Date()) { data, error in
            guard let activityData = data, error == nil else {
                print("There was an error getting the data: \(String(describing: error))")
                return
            }
            print((Double(activityData.distance!.intValue)/Double(1000))) // Print out optional distance in of walking and running in meters. / 1000 to convert from meter to km.
        }

Print gives me: 0.106

Answer 1

您可以使用 SwiftMeasurement 类型来转换长度单位并使用MeasurementFormatter 将其显示给用户:

let number: NSNumber = 106
let measurement = Measurement(value: number.doubleValue, unit: UnitLength.meters).converted(to: .kilometers)

let mf = MeasurementFormatter()
mf.unitOptions = .providedUnit
mf.unitStyle = .medium
mf.numberFormatter.maximumFractionDigits = 1
mf.string(from: measurement)   // "0.1 km"

就您而言:

guard let value = activityData.distance?.doubleValue else { return }
let measurement = Measurement(value: value, unit: UnitLength.meters).converted(to: .kilometers)

let mf = MeasurementFormatter()
mf.unitOptions = .providedUnit
mf.unitStyle = .medium
mf.numberFormatter.maximumFractionDigits = 1
mf.string(from: measurement)   // "0.1 km"