Error when delegating initialization in swift struct - swift

Question

I am trying to use another initalizer when some edge case happens during initialization, but I realized that once I delegate initialization to another initalizer, I can't treat that initializer like I would a normal one, instead I have to delegate initialization in all code branches.
(real use case is to initialize a struct containing email and name from a ASAuthorizationAppleIDCredential But because this object only returns the email and name the first time the user signs up with Apple, I have to check if it contains it, if no then an initalizer is called, that can create one by loading it from NSUbiquitousKeyValueStore. I ended up solving this by creating a function returning this struct instead of an init function)
The errors I get are
'self' used before 'self.init' call or assignment to 'self'
'self.init' isn't called on all paths before returning from initializer
These come up when I try to use a different initializer in a guard statement's else closure. Here is a simplified example:
struct Test {
var name : String
var age : Int
init(name : String) {
self.name = name
self.age = -1
}
init(name : String, age : Int?) {
guard let age = age else {
self.init(name: name)
return
}
self.name = name
self.age = age
}
}
Another solution I found is to create an init that can be called after the guard statement, in this case:
init(name: String, age : Int) {
self.name = name
self.age = age
}
and then use this init instead of assigning values directly.
My question is: why is this the case, and where is this behaviour mentioned or explained? The only documentation I found about this was the swift docs here:
https://docs.swift.org/swift-book/LanguageGuide/Initialization.html#ID215

Answer 1

Not sure about other languages but in Swift you have to first initialise existing initialiser before initialising extra property/properties.
import UIKit
struct Test {
var name : String
var age : Int
init(name : String) {
self.name = name
self.age = -1
}
init(name : String, age : Int?) {
self.init(name: name)
if let age = age {
self.name = name
self.age = age
}
}
}
let x = Test(name: "x", age: nil)
let y = Test(name: "y", age: 18)
let z = Test(name: "z")