Thanks to this code you can create dictionary with enums and range

Dictionary with range

import Foundation

extension Dictionary where Key == Range<Float> {
    subscript(bmi bmi: Float) -> Value? {
        guard let k = keys.filter({$0 ~= bmi}).first else {
            return nil
        }
        return self[k]
    }
}

import Foundation

extension Range : Hashable {
    public var hashValue: Int {
        return "\(lowerBound) to \(upperBound)".hashValue
    }
}


enum ABCD {
    case a, b, c, d
    
    static let dict: [Range<Float>: ABCD] = [
        0.0 ..< 18.5: ABCD.a,
        18.5 ..< 25.0: ABCD.b,
        25.0 ..< 30: ABCD.c,
        30 ..< MAXFLOAT: ABCD.d
    ]

}