Swift 错误：无法构造“Human”，因为它没有可访问的初始值设定项

Question

I am trying to instantiate an object from a class in swift. When I instantiate I am getting this error:

'Human'cannot be constructed because it has no accessible initializers

My Codes:

class Human{
    var firstName: String
    var lastName : String
    var age : Int
    var spouseName: String?
    var childName : String?
    var currentSpeed: Double = 0

    func walk(speedIncrease: Double){
        currentSpeed += speedIncrease*2
    }
    func brake(){
        self.currentSpeed = 0
    }
}  

let  tanvir = Human(firstName: "tanvir", lastName:"Alam", age: 32, currentSpeed:30)
print("gmk")

What am I doing wrong? Please Explain. Thank You.

Answer 1

Unlike structs where the initializer is synthesized classes require an explicit init method.

Add

init(firstName : String, lastName: String, age: Int, currentSpeed: Double = 0.0 {
    self.firstName = firstName
    self.lastName = lastName
    self.age = age
    self.currentSpeed = currentSpeed
}

and remove the default value of currentSpeed

A much simpler solution is to replace class with struct .