Nested Struct in Class, how to write an initializer-CodePudding

I'm trying to write some program that calculates Age from the current date. The main rule is: BirthDate should be a Structure nested in Class

How do I write an initializer for that?

for example what I want to see: let myStudent = StudentClass(name: "John", age: BirthDate(10, 10, 1995), gpa: 3.3) will save myStudent.age 10.10.1995 as 26

class StudentClass {
var name: String
var age: UInt8
var gpa: Double

struct BirthDate {
    var day: UInt8
    var month: UInt8
    var year: UInt16

    var calculatedAge: UInt8 {
        let date = Date()
        let calendar = Calendar.current
        let components = calendar.dateComponents([.year, .month, .day], from: date)
        let currYear =  UInt16(components.year!)
        let currMonth = components.month
        let currDay = components.day

        return UInt8(currYear - year) //it's not finished yet, just testing
    }
}

init(name: String, age: (day: UInt8, month: UInt8, year: UInt16), gpa: Double) {
    self.name = name
    self.age = BirthDate.init(day: day, month: month, year: year)
    self.gpa = gpa
}
}

CodePudding user response：

import Foundation

class StudentClass {
var name: String
var age: UInt8
var gpa: Double

struct BirthDate {
    let day: UInt8
    let month: UInt8
    let year: UInt16

    var calculatedAge: UInt8 {
        let date = Date()
        let calendar = Calendar.current
        let components = calendar.dateComponents([.year, .month, .day], from: date)
        let currYear =  UInt16(components.year!)
        let currMonth = components.month
        let currDay = components.day

        return UInt8(currYear - year) // write your age calculator code here
    }
}

init(name: String, birthDate: BirthDate, gpa: Double) {
    self.name = name
    self.age = birthDate.calculatedAge
    self.gpa = gpa
}
}

//Example
let aStudent = StudentClass(name: "John Doe", birthDate: StudentClass.BirthDate(day: 1,month: 01,year: 1991), gpa: 8)
        print(aStudent.age)

CodePudding user response：

Based on the code you provided, there is no need to create instance of BirthDate just to calculate age and assign it to age property. You can make your age property lazy that means it does not have to be instantiated at init but it will be instantiated when you first use it.

    class StudentClass {
    var name: String
    lazy var age: UInt8 = calculatedAge
    var gpa: Double
    
    var calculatedAge: UInt8 {
        let date = Date()
        let calendar = Calendar.current
        let components = calendar.dateComponents([.year, .month, .day], from: date)
        let currYear =  UInt16(components.year!)
        let currMonth = components.month
        let currDay = components.day
        let year: UInt16 = 2021 //lets say
        
        return UInt8(currYear - year) //it's not finished yet, just testing
    }
    
    init(name: String, age: (day: UInt8, month: UInt8, year: UInt16), gpa: Double) {
        self.name = name
        self.gpa = gpa
    }
}