从空的Swift数组获取对象类型 [英] Get object type from empty Swift Array
问题描述
有没有办法从空数组中获取数组元素的实例? (我需要动态
属性,因为我在 NSObject
中使用了一些KVC方法)
import Foundation
$ b class BaseClass:NSObject {
func myFunction(){
doWork()
}
}
class Car:BaseClass {
dynamic var id:Int = 0
}
class Bus:BaseClass {
动态var变量:Int = 0
}
var cars = Array< Car>()
我需要的是从这个空数组中获取空Car对象的实例,例如:
var carFromArray = cars.instanceObject()//将返回空Car对象
我知道我可以使用:
var object = Array< Car> .Element()
但是这对我不起作用,因为我从函数参数获取数组,并且我不知道它是元素类。
我试图写我自己的ty PE会做到这一点,它的工作原理,但我不能标记为动态
,因为它不能在Objective C中表示。我试图写入数组的扩展
扩展数组{
func instanceObject< T:BaseClass>() - > T' {
return T()
}
}
但是当我使用它,它有时会抛出错误致命错误:NSArray元素无法匹配Swift数组元素类型
let cars = [Car]( )// []
let arrayType = type(of:cars)// Array< Car> .Type
let carType = arrayType.Element.self // Car.Type
String :carType)//Car
Is there a way to get instance of Array element from the empty array? (I need dynamic
properties because I use some KVC methods on NSObject
)
import Foundation
class BaseClass: NSObject {
func myFunction() {
doWork()
}
}
class Car: BaseClass {
dynamic var id: Int = 0
}
class Bus: BaseClass {
dynamic var seats: Int = 0
}
var cars = Array<Car>()
What I need is a vay to get instance of empty Car object from this empty array, for example like this:
var carFromArray = cars.instanceObject() // will return empty Car object
I know that I can use:
var object = Array<Car>.Element()
but this doesn't work for me since I get array from function parameter and I don't know it's element class.
I have tried to write my own type that will do this, and it works, but then I cannot mark it as dynamic
since it cannot be represented in Objective C. I tried to write extension of Array
extension Array {
func instanceObject<T: BaseClass>() -> T? {
return T()
}
}
but when I use it, it sometimes throws error fatal error: NSArray element failed to match the Swift Array Element type
Swift 3: Get an empty array's element type:
let cars = [Car]() // []
let arrayType = type(of: cars) // Array<Car>.Type
let carType = arrayType.Element.self // Car.Type
String(describing: carType) // "Car"
这篇关于从空的Swift数组获取对象类型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!