iOS Swift 过滤器和生成模型需要太多时间

Question

我有 3 个模型和各自的数组

struct A {
    var id: String
    var bId: String
    var cId: String
}

struct B {
    var id: String
}

struct C {
    var id: String
}


let aList: [A] = [.......] // 100 elements

let bList: [B] = [.......] // 200 elements

let cList: [C] = [.......] // 300 elements

现在我需要结构 'FilterModel' 的对象数组，它将通过迭代 'bList' 和 'cList' 进行过滤strong>aList'

struct FilterModel {

    var objA: A
    var objB: B?
    var objC: C?

    init(objA: A,
         objB: B? = nil,
         objC: C? = nil) {

         self.objA = objA
         self.objB = objB
         self.objC = objC
    }
}

So far i have tried like this


var filterModels: [FilterModel] = []

for aModel in aList {

    let filterBModel = bList.filter { $0.id == aModel.bId }.first
    let filterCModel = cList.filter { $0.id == aModel.cId }.first

    let model =  FilterModel(objA: aModel,
                             objB: filterBModel,
                             objC: filterCModel)

    filterModels.append(model)
}

时间太长，有什么优化或者更好的办法吗？

Answer 1

由于 aList 的每次迭代都必须迭代两个列表，因此复杂性并不好。相反，首先生成索引:

var bIndex: [String: B] = [:]
bList.forEach {
   bIndex[$0.id] = $0
} 

var cIndex: [String: C] = [:]
cList.forEach {
   cIndex[$0.id] = $0
} 

let filterModels: [FilterModel] = aList.map { aModel in
   return FilterModel(
      objA: aModel,
      objB: bIndex[aModel.bId],
      objC: cIndex[aModel.cId]
   )
}