Kdan

enum PersonCodingKeys: String, CodingKey {
  case name
  case pets
}

// CHALLENGE 1: Nested Heterogeneous Array Decoded.
required init(from decoder: Decoder) throws {
  let container = try decoder.container(keyedBy: PersonCodingKeys.self)
  name = try container.decode(String.self, forKey: .name)
  

Kdan

extension KeyedDecodingContainer {

    /// Decode a heterogeneous list of objects for a given family.
    /// - Parameters:
    ///     - family: The ClassFamily enum for the type family.
    ///     - key: The CodingKey to look up the list in the current container.
    /// - Returns: The resulting list of heterogeneousType elements.
    func decode<T : Decodable, U : ClassFamily>(family: U.Type, forKey key: K) throws -> [T] {
        var container = try self.nestedUnkeyedContainer(forKey: key)
        var list = [T]()

Kdan

// CHALLENGE 1: Nested Heterogeneous Array Decoded.
required init(from decoder: Decoder) throws {
  let container = try decoder.container(keyedBy: PersonCodingKeys.self)
  name = try container.decode(String.self, forKey: .name)
  pets = try container.decode(family: PetFamily.self, forKey: .pets)
}

Kdan

func totalDistance(of locations: [CLLocation]) -> CLLocationDistance {
    var distance: CLLocationDistance = 0.0
    var previousLocation: CLLocation?
    
    locations.forEach { location in
        if let previousLocation = previousLocation {
            distance += location.distance(from: previousLocation)
        }
        previousLocation = location
    }

Kdan

func totalDistance(initialDistance: CLLocationDistance, initialLocation: CLLocation?, locations: inout [CLLocation]) -> CLLocationDistance {
    if locations.isEmpty {
        return initialDistance
    } else if let initialLocation = initialLocation {
        let firstLocation = locations.removeFirst()
        let distance = firstLocation.distance(from: initialLocation)
        return totalDistance(initialDistance: initialDistance + distance, initialLocation: firstLocation, locations: &locations)
    }
    return totalDistance(initialDistance: initialDistance, initialLocation: locations.removeFirst(), locations: &locations)
}

Kdan

let closure: ((CLLocationDistance, CLLocation?), CLLocation) -> (CLLocationDistance, CLLocation?) = { tuple, location in
    guard let previousLocation = tuple.1 else {
        return (tuple.0, location)
    }
    return (tuple.0 + location.distance(from: previousLocation), location)
}

Kdan

let closure: ((CLLocationDistance, CLLocation?), CLLocation) -> (CLLocationDistance, CLLocation) = { tuple, location in
    return (tuple.0 + location.distance(from: tuple.1 ?? location), location)
}

Kdan

func totalDistance(of locations: [CLLocation]) -> CLLocationDistance {
    return locations.reduce((0.0, nil), { ($0.0 + $1.distance(from: $0.1 ?? $1), $1) }).0
}

Kdan

extension Array where Element: CLLocation {
  
    /// Returns the total distance of the list of CLLocation objects.
    var totalDistance: CLLocationDistance {
        return reduce((0.0, nil), { ($0.0 + $1.distance(from: $0.1 ?? $1), $1) }).0
    }
  
}

Kdan

import CoreLocation

/// The locations used for the examples.
let locations = [CLLocation(latitude: 10.0, longitude: 12.0),
                 CLLocation(latitude: 10.1, longitude: 12.0),
                 CLLocation(latitude: 10.2, longitude: 12.0),
                 CLLocation(latitude: 10.1, longitude: 12.0)]

/* A BOILERPLATE SOLUTION */