Question

我的下面的功能偶尔会产生一个无穷大的数字。我以为我可以使用下面的舍入函数来避免使用无限数...换句话说1.333333333333（INF）四舍五入到1.33，但编译器仍将INF.rounded的结果视为无限，我怎么能舍入所以我仍然可以在这里推出一个值？特别是我正在尝试编码为JSON并收到此错误：

metadata ERROR = invalidValue(inf, Swift.EncodingError.Context(codingPath: [Watch_Extension.HockeyTrackerMetadata.(CodingKeys in _B2A7010AF20490DAF638D1E0A01E4982).maximumCapableSpeed], debugDescription: "Unable to encode Double.infinity directly in JSON. Use JSONEncoder.NonConformingFloatEncodingStrategy.convertToString to specify how the value should be encoded.", underlyingError: nil))

//Calculation  
 func calculateMaximumAndAverageSkatingEfficiency() {

        let heartRateUnit:HKUnit = HKUnit(from: "count/min")
        let heartRatesAsDouble = heartRateValues.map { $0.quantity.doubleValue(for: heartRateUnit)}
        let maxHeartRate = heartRatesAsDouble.max()
        guard let maxHeartRateUnwrapped = maxHeartRate else { return }

        maximumEfficiencyFactor = ((1760.0 * (maxSpeed / 60)) / maxHeartRateUnwrapped).round(to: 2)

        guard let averageIceTimeHeartRateUnwrapped = averageIceTimeHeartRate else { return }

        averageEfficiencyFactor = ((1760.0 * (averageSpeed / 60)) / averageIceTimeHeartRateUnwrapped).round(to: 2)

    }

//Round extension I am using
extension Double {

    func round(to places: Int) -> Double {
        let divisor = pow(10.0, Double(places))
        return Darwin.round(self * divisor) / divisor
    }

}

//Usage 
  if let averageEfficiencyFactorUnwrapped = averageEfficiencyFactor {
            metadata.averageEfficiencyFactor = averageEfficiencyFactorUnwrapped.round(to: 2)
        }

Answer 1

＆＃34;无限的价值＆＃34;意味着该值为正或负无穷大，可能是因为它是零除或类似数学运算的结果。这并不意味着该值是非终止小数。

确保maxHeartRateUnwrapped和averageIceTimeHeartRateUnwrapped不为零。

如何从Swift中的无限数中导出一个值？

1 个答案: