SampleUsingGuardCheckConditions.swift

struct Student {
    let name: String?
    let age: Int?
    let gender: String?
}

let student = Student(name: "Rio", age: 27, gender: "Male")

func validateStudentInfo (_ student: Student) -> String {
    // We do NOT need to using student name, just want to check if
    // student name have value, so using underscore here
    if let _ = student.name {
        if let _ = student.age {
            if let _ = student.gender {
                return "OK"
            } else {
                return "Gender not valid"
            }
        } else {
            return "Age not valid"
        }
    } else {
        return "Name not valid"
    }
}

func validateStudentInfoWithGuard (_ student: Student) -> String {
    guard let _ = student.name else {
        return "Name not valid"
    }
    
    guard let _ = student.age else {
        return "Age not valid"
    }
    
    guard let _ = student.gender else {
        return "Gender not valid"
    }
    
    return "OK"
}

validateStudentInfo(student)
validateStudentInfoWithGuard(student)