如何有条件地将结构分配给变量？

Question

The code is pretty self explanatory. I am trying to have the dictionary variable be one of 3 structs. There is likely a simple solution that escapes me at the moment.

func whichDictionaryToUse(flaps: Int, wind: Int) {

var dictionary = ()
var possibleWindDictionaries = Set<[Double:Double]>()

switch flaps {
case 10: dictionary = CorrectLD10Dict()
case 15: dictionary = CorrectLD15Dict()
case 35: dictionary = CorrectLD35Dict()
default: print("Present alert saying flaps value out of range")
}

switch wind {
  case 10: possibleWindDictionaries = [dictionary.plusTenMinusTwoDic, dictionary.plusTenMinusOneDic, dictionary.plusTenZeroDic, dictionary.plusTenPlusOneDic, dictionary.plusTenPlusTwoDic]
 …

Answer 1

struct CorrectLD10Dict: CorrectLDict {}
struct CorrectLD15Dict: CorrectLDict {}
struct CorrectLD35Dict: CorrectLDict {}

protocol CorrectLDict {}

func whichDictionaryToUse(flaps: Int, wind: Int) {
    
    let dictionary: CorrectLDict
    var possibleWindDictionaries = Set<[Double:Double]>()
    
    switch flaps {
    case 10: dictionary = CorrectLD10Dict()
    case 15: dictionary = CorrectLD15Dict()
    case 35: dictionary = CorrectLD35Dict()
    default: print("Present alert saying flaps value out of range")
    }
    
    switch wind {
      case 10: possibleWindDictionaries = [dictionary.plusTenMinusTwoDic, dictionary.plusTenMinusOneDic, dictionary.plusTenZeroDic, dictionary.plusTenPlusOneDic, dictionary.plusTenPlusTwoDic]
     …
}