How to create a dictionary having string and function as key value pair in swift - swift

Question

I am looking to create a dictionary that will have
let urlDict:[String:Func] = ["LOGIN":getLoginURL(), "RESET":getResetPasswordURL()]
func getLoginURL() -> String{
if (sandbox == true){
return sb_login_url
}else{
return live_login_url
}
}
func getResetPasswordURL() -> String{
if (sandbox == true){
return sb_reset_url
}else{
return live_reset_url
}
}
The purpose of this dict is to get/map functions based on the KEY and as per KEY corresponding function must be called which in turn will return return urls.
I have tried naming the dictionary but I am unable to do it
let urlDict:[String:Func] = ["LOGIN":getLoginURL(), "RESET":getResetPasswordURL()]
let urlDict:[String:Function] = ["LOGIN":getLoginURL(), "RESET":getResetPasswordURL()]
let urlDict:[String:Functions] = ["LOGIN":getLoginURL(), "RESET":getResetPasswordURL()]
EDIT 1
class Constants{
private let sb_login_url = "http://IP_ADDRESS_COM/login_with_credentials"
private let live_login_url = "http://google.com"
private let sb_reset_url = "http://IP_ADDRESS_COM/forgot_password"
private let live_reset_url = "http://google.com"
func getLoginURL() -> String{
if (sandbox == true){
return sb_login_url
}else{
return live_login_url
}
}
func getResetPasswordURL() -> String{
if (sandbox == true){
return sb_reset_url
}else{
return live_reset_url
}
}
` let urlDict: [String: () -> String] = ["LOGIN": Constants.getLog‌​inURL(), "RESET":Constants.getResetPasswordURL()]
if let getFunc = urlDict[url_key] {
let url = (getFunc()) // foo}
}

Answer 1

You must specify the type of the functions (which are common for both getLoginURL and getResetPasswordURL) for the value slot in the dictionary, namely () -> String, a zero-arguments function returning a String instance.
func getLoginURL() -> String {
return "foo"
}
func getResetPasswordURL() -> String {
return "bar"
}
let urlDict: [String: () -> String] =
["LOGIN": getLoginURL, "RESET":getResetPasswordURL]
/* ^^^^^^^^^^^- note that you do not _call_ the functions,
as this would result in a String instance */
// get a function reference from the dictionary and invoke it
if let getFunc = urlDict["LOGIN"] {
print(getFunc()) // foo
}
After your comments below, as well as your edit, it seems you want the get... functions to be class members if your class Constants (i.e., marked static).
class Constants {
static var sandbox = true
// I've just added this to test your example
private static let sb_login_url = "http://IP_ADDRESS_COM/login_with_credentials"
private static let live_login_url = "http://google.com"
private static let sb_reset_url = "http://IP_ADDRESS_COM/forgot_password"
private static let live_reset_url = "http://google.com"
static func getLoginURL() -> String {
if (Constants.sandbox == true){
return Constants.sb_login_url
}
else {
return Constants.live_login_url
}
}
static func getResetPasswordURL() -> String{
if (Constants.sandbox == true){
return Constants.sb_reset_url
}
else {
return Constants.live_reset_url
}
}
}
let urlDict: [String: () -> String] =
["LOGIN": Constants.getLoginURL, "RESET": Constants.getResetPasswordURL]
// get a function reference from the dictionary and invoke it
if let getFunc = urlDict["LOGIN"] {
print(getFunc()) // http://IP_ADDRESS_COM/forgot_password
Constants.sandbox = false
print(getFunc()) // http://google.com
}

Answer 2

You could simply create a global typealias to Function prototype and can use it anywhere in your project and you don't need to use () -> String everytime when you create Dictionary.
public typealias VoidToStringFunctio‌n = () -> String
func getLoginURL() -> String {
return "url"
}
func getResetPasswordURL() -> String {
return "password"
}
and use it like this
let urlDict : [String: VoidToStringFunctio‌n] = ["LOGIN": getLoginURL, "Password": getResetPasswordURL]