函数中缺少 return - 模型中出现 swift 错误

Question

因此，我在情节提要板上自行生成了饼图，其中包含各种标签、滑块、Age 按钮、CurrentAsset、Income 等。我正在使用 struct 构建模型，并且我不断收到具有 "missing return in a function expected to return 'Double'" 尽管您可以看到我有 returns 用于 currentAssetFactor、savingsFactor、bondFactor、toleranceFactor、outlookFactor。我做错了什么？

public struct AllocationModel
{
  let maxAge = 95.0
  let currentAge: Double

  let minCurrentAsset = 100000.0
  let maxCurrentAsset = 500000.0
  let currentAsset: Double

  let minSavings = 5000.0
  let maxSavings = 20000.0
  let currentSavings: Double

  let maxIncomeRequired = 0.04
  let minIncomeRequired = 0.01
  let currentIncomeRequired: Double

  let tolerance: String

  let outlook: String

  // MARK: - Methods

  public var currentAssetFactor: Double {
    if currentAsset > maxCurrentAsset {
      return 5.0
    } else if currentAsset >= minCurrentAsset {
      return Double(currentAsset / minCurrentAsset)
    }
  }

  public var savingsFactor: Double {
    if currentSavings >= maxSavings {
      return 4.0
    } else if currentSavings >= minSavings {
      return Double(currentSavings / minSavings)
    }
  }

  public var bondFactor: Double {
    if currentIncomeRequired >= maxIncomeRequired {
      return 0.2
    } else if currentIncomeRequired >= minIncomeRequired {
      return (0.05 * Double(currentIncomeRequired / minIncomeRequired) )
    }
  }

  public var toleranceFactor: Double {
    switch tolerance {
      case "conservative": return 0.0
      case "balanced": return 3.0
      case "aggressive": return 6.0
    default: 0.0
    }
  }

  public var outlookFactor: Double {
    switch outlook {
      case "poor": return 0.0
      case "moderate": return 7.0
      case "strong": return 10.0
    default: return 0.0
    }
  }


  public var stock: Double {
    return maxAge - currentAge + currentAssetFactor + savingsFactor + toleranceFactor + outlookFactor
  }

  public var nonStock: Double { return 100.0 - stock }

  public var bondPercentage: Double { return 0.35 + bondFactor }

  public var bond: Double { return nonStock * bondPercentage }

  public var cash: Double { return nonStock - bond }

  // MARK: - Init

  public init(currentAge: Double, currentAsset: Double, currentSavings: Double, currentIncomeRequired: Double, tolerance: String, outlook: String) {
    assert(currentAge > 0)

    self.currentAge = currentAge
    self.currentAsset = currentAsset
    self.currentSavings = currentSavings
    self.currentIncomeRequired = currentIncomeRequired
    self.tolerance = tolerance
    self.outlook = outlook
  }

}

Answer 1

您并未涵盖所有情况。考虑您的一种方法：

  public var currentAssetFactor: Double {
    if currentAsset > maxCurrentAsset {
      return 5.0
    } else if currentAsset >= minCurrentAsset {
      return Double(currentAsset / minCurrentAsset)
    }
  }

很好。那么如果第一个 if 失败（例如 currentAsset 是 而不是 大于 maxCurrentAsset）并且第二个 if 失败（例如 currentAsset 是不是大于或等于 minCurrentAsset)？现在我们什么都不 return！

所以你的逻辑有问题。而且编译器很聪明——比你聪明！它如此聪明，它发现了您逻辑中的这个漏洞，并阻止您继续前进。您需要以 向编译器证明 涵盖所有可能性的方式重写您的方法，即您将 always return 一个值，无论如何。

函数中缺少 return - 模型中出现 swift 错误

Missing return in a function - swift error in Model

struct

model

compiler-errors

ios

swift