using functions in swift - swift

Question

I'm new to programming. Please tell me what is wrong in this code! Why am I getting the output "(Function)"?
//first function
func admit(person: String) -> String {
return("\(person) can go")
}
//second function
func deny(person: String) -> String {
return("\(person) can not go")
}
//third function
func screen(onGuestList: String, person: String) -> (String) -> String {
if onGuestList == "yes"{
return admit(person:)
} else {
return deny(person:)
}
}
var outcome = screen(onGuestList: "yes", person: "Sapinder")
print(outcome)
I expect the output of "(person) can go", but the actual output is "(Function)".

Answer 1

Why am I getting the output "(Function)"?
because screen function is not returning a String, it returns (String) -> String instead.
Simply, the fix for it is to implement screen as:
func screen(onGuestList: String, person: String) -> String {
if onGuestList == "yes"{
return admit(person: person)
} else {
return deny(person: person)
}
}
so what is the difference here? Well, first of all now it returns a string instead of a function that takes a string and returns a string. Also, for calling admit and deny you have to mention the label (person) to pass a parameter to them.
Unrelated tip:
func screen(onGuestList: String, person: String) -> String {
return onGuestList == "yes" ? admit(person: person) : deny(person: person)
}
preferably, try to name the functions as verbs instead of nouns, we usually do this for properties (fields) but not methods (behaviors). For example: displayScreen instead of screen.
So what's the meaning of returning (String) -> String?
Briefly, Swift does allow such a thing. Consider the following example:
func sayHello() -> (String) -> String {
let functionToReturn: (String) -> String = { name in
return "Hello \(name)"
}
return functionToReturn
}
func takeMy(function: (String) -> String, name: String) {
print("I am about to print the function:")
print(function(name))
}
takeMy(function: sayHello(), name: "Sappie")
// I am about to print the function:
// Hello Sappie
as you can see, takeMy function is that takes another function as a parameter of type (String) -> String, therefore we passed sayHello() for it since it's signature matches the parameter type.
As a real world example, you could find many methods that parameters as functions when working with collections (for instance). As an example, the filter method:
func returnMoreThanfive(element: Int) -> Bool {
return element > 5
}
let array = [1,2,3,4,5,6,7,8,9]
let filteredArray = array.filter(returnMoreThanfive)
// [6, 7, 8, 9]
we passed to filter a function that takes an element and returns a boolean. Keep in mind It's just an example to make it more clear to you, however we usually do like this:
let filteredArray = array.filter { $0 > 5 }

Answer 2

Try
func admit(person: String) -> String {
return("\(person) can go")
}
//second function
func deny(person: String) -> String {
return("\(person) can not go")
}
//third function
func screen(onGuestList: String, person: String) -> String {
if onGuestList == "yes"{
return admit(person: person)
} else {return deny(person: person)
}
}
var outcome = screen(onGuestList: "yes", person: "Sapinder")
print(outcome)
What you were doing were returning a (String) -> String instead of String
In swift you can return a Function as a return type