Swift: for loop, search dictionary, set variables from keys - swift

Question

Error is: Cannot convert value of type (String: Int)? to specified type 'String'.
Obviously my dictionary 'roster' is 'String: Int' and the local variables ('lastPlayer' and 'firstPlayer') inside function 'printRoster' is String. But I've tried every variation with no luck. It worked fine before I made roster a dictionary, and it was just a String.
What it should do: function concatenates a string so that it has correct punctuation. First string is "The roster includes", then we add on each player located in the Key of the dictionary 'roster'. But the first key in the roster gets no comma and the last key gets an ', and'.
Also, can I add the dictionary 'roster' to the protocol, didn't see the syntax in any of the Apple manuals
import UIKit
protocol basketballTeams {
var teamName: String? { get }
var numberOfPlayers: Int? { get }
var locatedIn: String? { get }
func printTeamLocation()
}
class BasketballTeam {
var teamName: String?
var numberOfPlayers: Int?
var locatedIn: String?
var roster = [String: Int]()
init(teamName: String) {
self.teamName = teamName
}
func printTeamLocation() -> String {
return "The \(teamName) are located in \(locatedIn)"
}
func printRoster() -> String {
var rosterPrint = "The roster includes"
for player in roster.keys {
rosterPrint += player
var firstPlayer: String = roster.first
var lastPlayer = roster.last
if (player == firstPlayer) {
rosterPrint += " \(player)"
}
else if (player == lastPlayer) {
rosterPrint += ", and \(player)."
}
else {
rosterPrint += ", \(player)"
}
}
return rosterPrint
}
}
enum NumberedPosition: Int {
case PointGuard = 1
case ShootingGuard, SmallForward, PowerForward, Center
func labelOfPosition() -> String {
switch self {
case .PointGuard:
return "Point Guard"
case .ShootingGuard:
return "Shooting Guard"
case .SmallForward:
return "Small Forward"
case .PowerForward:
return "Power Forward"
case .Center:
return "Center"
default:
"Position doesn't exit"
}
}
}
let goldenStateWarriors = BasketballTeam(teamName: "Golden State Warriors")
goldenStateWarriors.numberOfPlayers = 12
goldenStateWarriors.locatedIn = "Oakland, California"
goldenStateWarriors.roster = ["Stephen Curry" : 1, "Andrew Bogut" : 5, "Klay Thompson" : 2]
goldenStateWarriors.roster["Harrison Barnes"] = 3

Answer 1

How about this:
let roster = ["Stephen Curry":1, "Andrew Bogu": 2, "Klay Thompson":3]
let players = roster.keys.joined(separator: ", ")
let all = "Roster contains: \(players)."

Answer 2

If you still want to add the "and" to the last row you can use this function:
func printRoster() -> String {
var rosterPrint = "The roster includes"
let arr = Array(roster.keys)
let firstPlayer: String = arr.first!
let lastPlayer: String = arr.last!
for (player, _ ) in roster {
switch player {
case firstPlayer:
rosterPrint += " \(player)"
case lastPlayer:
rosterPrint += ", and \(player)."
default:
rosterPrint += ", \(player)"
}
}
return rosterPrint
}
and call it like so:
print(goldenStateWarriors.printRoster())

Answer 3

Given this dictionary
let roster = ["Stephen Curry":1, "Andrew Bogu": 2, "Klay Thompson":3]
you can
let elms = roster
.keys
.reduce("") { $0.1 + ", " + $0.0 }
.characters
.dropLast()
.dropLast()
let res = "The roster includes " + String(elms)
Result
"The roster includes Andrew Bogu, Stephen Curry, Klay Thompson"
Update #1: Using the FOR LOOP
Since you want to use the for loop here's the code
let roster = ["Stephen Curry":1, "Andrew Bogu": 2, "Klay Thompson":3]
var result = "The roster includes "
for (index, elm) in roster.keys.enumerate() {
result += elm
if index < roster.keys.count - 1 {
result += ", "
}
}
print(result) // The roster includes Klay Thompson, Stephen Curry, Andrew Bogu
Update #2: Using the FOR LOOP with first and last
let roster = ["Stephen Curry":1, "Andrew Bogu": 2, "Klay Thompson":3]
func printRoster() -> String {
var rosterPrint = "The roster includes"
let players = Array(roster.keys)
guard let
first = players.first,
last = players.last
else { return "" } // this is ugly, it should return nil instead...
for player in players {
switch player {
case first: rosterPrint += " \(player)"
case last: rosterPrint += ", and \(player)."
default: rosterPrint += ", \(player)"
}
}
return rosterPrint
}
printRoster() // "The roster includes Klay Thompson, Stephen Curry, and Andrew Bogu."

Answer 4

This seems to work well, at least until they allow .first and .last with dictionaries (if that's even possible).
class BasketballTeam {
var teamName: String?
var numberOfPlayers: Int?
var locatedIn: String?
var roster = [String: Int]()
init(teamName: String) {
self.teamName = teamName
}
func printTeamLocation() -> String {
return "The \(teamName) are located in \(locatedIn)"
}
func printRoster() -> String {
var rosterPrint = "The roster includes"
let rosterArray = Array(roster.keys)
for player in rosterArray {
let firstPlayer = rosterArray.first
let lastPlayer = rosterArray.last
switch player {
case firstPlayer!:
rosterPrint += " \(player)"
case lastPlayer!:
rosterPrint += ", and \(player)."
default:
rosterPrint += ", \(player)"
}
}
return rosterPrint
}
}
Full code, you can paste into a playground if you're trying to learn swift and familiar with basketball
import UIKit
protocol basketballTeams {
var teamName: String { get }
var numberOfPlayers: Int { get }
var locatedIn: String { get }
var roster: [String: Int] { get }
func printTeamLocation()
}
class BasketballTeam {
var teamName: String?
var numberOfPlayers: Int?
var locatedIn: String?
var roster = [String: Int]()
init(teamName: String) {
self.teamName = teamName
}
func printTeamLocation() -> String {
return "The \(teamName) are located in \(locatedIn)"
}
func printRoster() -> String {
var rosterPrint = "The roster includes"
let rosterArray = Array(roster.keys)
for player in rosterArray {
let firstPlayer = rosterArray.first
let lastPlayer = rosterArray.last
switch player {
case firstPlayer!:
rosterPrint += " \(player)"
case lastPlayer!:
rosterPrint += ", and \(player)."
default:
rosterPrint += ", \(player)"
}
}
return rosterPrint
}
}
enum NumberedPosition: Int {
case PointGuard = 1
case ShootingGuard, SmallForward, PowerForward, Center
func labelOfPosition() -> String {
switch self {
case .PointGuard:
return "Point Guard"
case .ShootingGuard:
return "Shooting Guard"
case .SmallForward:
return "Small Forward"
case .PowerForward:
return "Power Forward"
case .Center:
return "Center"
default:
"Position doesn't exist"
}
}
}
let goldenStateWarriors = BasketballTeam(teamName: "Golden State Warriors")
goldenStateWarriors.numberOfPlayers = 12
goldenStateWarriors.locatedIn = "Oakland, California"
goldenStateWarriors.roster = ["Stephen Curry" : 1, "Andrew Bogut" : 5, "Klay Thompson" : 2]
goldenStateWarriors.roster["Harrison Barnes"] = 3
goldenStateWarriors.printRoster()
goldenStateWarriors.printTeamLocation()
var num = 3
if let numberToPositionConv = NumberedPosition(rawValue: num) {
let description = numberToPositionConv.labelOfPosition()
}