计算一个类迅速实例的数量 [英] count number of instances of a class swift

问题描述

如何计算Swift中一个类的实例数量？我有以下课程：

  class car {
 static var car人口：Int = 0 
 var color ：字符串
 var容量：Int 
 var驱动程序：布尔？ 
 var carOn：布尔=假
 init（carColor：String，carCapacity：Int）{
 self.capacity = carCapacity 
 self.color = carColor 
 car人口++ // #########给我错误############## 
} 
 func startCar（）{
 self.carOn = true 
} 
} 
 
类赛车：car {
 var nitro：Bool 
 init（carColor：String，carCapacity：Int，hasNitro：Bool） {
 self.nitro = hasNitro 
 super.init（carColor：carColor，carCapacity：carCapacity）
} 
} 
 
 car.CarPopulation //输出在xcode操场上$ 0 
  

我假设我需要一个函数来实际返回值，但是我想要

我收到以下错误：

错误：静态成员'carPopulation'不能用于类型'car'的实例

解决方案

内部初始化方法中，您必须使用

  Car.carPopulation + = 1 $ b向静态var中添加一个$ b  

您必须实施反初始化程序以删除将要消失的汽车实体

  deinit 
 {
 Car.carPopulation-= 1 
} 
  

How do you count the number of instances of a class in Swift? I have the following class:

class car {
    static var carPopulation: Int = 0
    var color: String
    var capacity: Int
    var driver: Bool?
    var carOn: Bool = false
    init (carColor: String, carCapacity: Int) {
        self.capacity = carCapacity
        self.color = carColor
        carPopulation ++ //##########GIVES ME ERROR#############
    }
    func startCar() {
        self.carOn = true
    }
}

class raceCar : car {
    var nitro: Bool
    init(carColor: String, carCapacity: Int, hasNitro: Bool) {
        self.nitro = hasNitro
        super.init(carColor: carColor, carCapacity: carCapacity)
    }
}

car.CarPopulation //outputs 0 in xcode playground

I am assuming I need a function to actually return the value, but I want the counter to increase every time an instance of the class is created.

I get the following error:

error: static member 'carPopulation' cannot be used on instance of type 'car'

解决方案

Inside initializer method you have to add one to your static var with

Car.carPopulation += 1

And you must implement de deinitializer to delete the car entity that is going to disappear

deinit
{
    Car.carPopulation -= 1
}

这篇关于计算一个类迅速实例的数量的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！