I've been reading the formal book of swift.

https://docs.swift.org/swift-book/LanguageGuide/Initialization.html

according to the document

The following two snippets are the same

struct Fahrenheit {
    var temperature: Double
    init() {
        temperature = 32.0
    }
}
var f = Fahrenheit()

struct Fahrenheit {
    var temperature = 32.0
}

var f = Fahrenheit()

What's the whole point of initializer ?

I could just make a new instance everytime by using let or var and then call the struct and give each property a value, isn't this good enough ?

Day 10: Structs

If you go back to Day 10 of your 100 Days of SwiftUI journey, you'll recall the introduction to Structs.

@twostraws introduces the concept of memberwise initializers. I admit it. This is not the most friendly description to toss on a learner just 10 days into a course. This is a mouthful of jargon.

But Lecture 10 should answer your question. Structs, by default, can be initialized by just providing values for each public parameter defined in your struct! You get a free initializer by default. Please convince yourself that private variables (i.e. @State private var) are NOT included in the default initializer. Also, convince yourself that computed properties are not available in the default initializer either.

But as @rooster notes, as you move along your SwiftUI journey, you'll find the need to have a more clever way to initialize some of your structs. In this case, you'll want to craft your own initializer. Indeed, you may want to craft one or more initializers for a Struct.

I agree with comrade @rooster here. Please enjoy the journey! Keep reading!

If you don't provide default values in your struct then you need a way to enter those values when you create an instance of the struct.

struct Person {
    var firstName: String
    var middleName: String
    var lastName: String
    let ethnicity: String
    var height: Int
    var weight: Int
}
let me = Person(firstName: <#T##String#>, middleName: <#T##String#>, lastName: <#T##String#>, ethnicity: <#T##String#>, height: <#T##Int#>, weight: <#T##Int#>)

thank you guys.

Didn't expect to have so many answers on the Christmas Day !

Happy Holidays everyone