Counting number of instances inside a struct in swift - swift

Question

I'm very new to Swift and I can't figure this one out. I need to count the number of instances created inside a struct. Since I created 3 instances, how can I get the program to tell me there are three? I tried the exNames.count at the end, but that doesn't work... Thanks!
struct People {
let name: String
var age: Int
let sex: Character
}
var heather = People(name: "Heather", age: 32, sex: "F")
var peter = People(name: "Peter", age: 34, sex: "M")
var scott = People(name: "Scott", age: 27, sex: "M")
let exNames = [People]()
exNames.count

Answer 1

You want to use a static variable on the People struct. However, this does require overriding the default initializer.
struct People
{
static var instances = 0
let name:String
var age:Int
let sex:Character
init(name:String, age:Int, sex:Character)
{
self.name = name
self.age = age
self.sex = sex
People.instances += 1
}
}
var heather = People(name: "Heather", age: 32, sex: "F")
var peter = People(name: "Peter", age: 34, sex: "M")
var scott = People(name: "Scott", age: 27, sex: "M")
let exNames = [People]()
/* exNames.count only gives the number of People that are
contained in this particular array, which is zero. */
print(People.instances) // 3
If you want to decrement the count when the structs go out of scope, you need to upgrade to a class which provides a deinitializer deinit {}.
Note that the “proper” use cases for a static counter are exceedingly limited. It is very likely that the problem you are actually trying to solve would be better served by a different hammer.
By the way, you really shouldn’t be using Character to represent sex, as Character in Swift is very closely tied to strings, and so they are built and optimized for lexical purposes, not for flagging. It also opens the door for a lot of potential bugs, as Swift won’t be able to verify valid input as well (what if someone accidentally passes a sex value of "#"?) Instead, use the built in Bool type, or a custom enum if you need more functionality.

Answer 2

Looks like you wanted to create an array of people, in that case:
struct People {
let name: String
var age: Int
let sex: Character
}
var heather = People(name: "Heather", age: 32, sex: "F")
var peter = People(name: "Peter", age: 34, sex: "M")
var scott = People(name: "Scott", age: 27, sex: "M")
//This should be a var, because you are going to modify it
var exNames = [People]()
exNames.append(heather)
exNames.append(peter)
exNames.append(scott)
exNames.count