如何使用构造函数将自定义类型转换为数组?
extension Array where Generator.Element == Int{ // same-type requirement makes generic parameter 'Element' non-generic
// `where Element: SignedIntegerType` would work but that is a protocol
init(_ value:Custom){
self = [value.item1, value.item2, value.item3, value.item4 ] // cannot assign value of type '[Int]' to type 'Array<_>'
}
}
struct Custom{
// let array = [item.........] I could also have an array here but that is not the point of the question.
private let item1:Int
private let item2:Int
private let item3:Int
private let item4:Int
init(_ value1:Int, _ value2:Int, _ value3:Int, _ value4:Int ){
self.item1 = value1
self.item2 = value2
self.item3 = value3
self.item4 = value4
}
}
let custom = Array(Custom(2, 3, 4, 5))// I want to be be able to convert to an array/set.
编辑:我认为这可能是swift 2.1的限制
答案 0 :(得分:1)
我不确定为什么你需要它作为数组类型的扩展。
您的struct(或类)可以只使用一个方法将其内容作为数组返回。语法略有不同,但就我的例子而言,结果将是相同的。
struct Custom<T>
{
private let item1:T
private let item2:T
private let item3:T
private let item4:T
init(_ value1:T, _ value2:T, _ value3:T, _ value4:T )
{
self.item1 = value1
self.item2 = value2
self.item3 = value3
self.item4 = value4
}
var array:[T] { return [item1, item2, item3, item4] }
}
let custom = Custom(2, 3, 4, 5).array
答案 1 :(得分:1)
使用自定义类型的Swift 3示例:
假设您将MyCustomType作为自定义类:
class MyCustomType
{
var name = ""
var code = ""
convenience init(name: String, code: String)
{
self.init()
self.name = name
self.code = code
}
}
您可以这样扩展数组:
extension Collection where Iterator.Element == MyCustomType
{
func getNameFrom(code: String) -> String?
{
for custom in self {
if custom.code == code {
return custom.name
}
}
return nil
}
}
用法:
let myCustomArray = [MyCustomType]()
myCustomArray.getNameFrom(code: "code")
希望它有所帮助! :)
答案 2 :(得分:0)
这个怎么样?:
ListView
或简化为:
struct Custom{
private let item1:Int
private let item2:Int
private let item3:Int
private let item4:Int
init(_ value1:Int, _ value2:Int, _ value3:Int, _ value4:Int ){
self.item1 = value1
self.item2 = value2
self.item3 = value3
self.item4 = value4
}
var array : [Int] {
get {
return [self.item1, self.item2, self.item3, self.item4]
}
}
}
let customArray = Custom(2, 3, 4, 5).array // [2, 3, 4, 5]
答案 3 :(得分:-1)
试着看看这个&#39;示例&#39;
struct Custom {
let array: [Int]
init(_ value: Int...) {
self.array = value.map({$0+1})
}
}
extension _ArrayType where Generator.Element == Int {
init(custom: Custom) {
self.init()
self.appendContentsOf(custom.array)
}
}
let custom = Custom(1,2,3)
let carr = Array(custom: custom)
print(carr, carr.dynamicType) // [2, 3, 4] Array<Int>
在您使用之前,回答这个问题 为什么不使用simly
let carr = custom.array
<强> ??? 强>