你如何计算Swift中一个类的实例数?我有以下类:计数一个类的实例数swift
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
我假设我需要一个函数实际返回的值,但我想柜台每增加创建类的实例的时间。
我得到以下错误:
error: static member 'carPopulation' cannot be used on instance of type 'car'
'Car.carPopulation + = 1'? (注意类名应以大写字母开头,'++'已弃用) – Hamish