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 struct 'FilterModel' 的对象数组，它将通过迭代 'bList' 和 'cList' 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)
}

是否有任何优化或更好的方法，因为它需要太多时间？

Answer 1

由于aList 的每次迭代都必须遍历两个列表，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]
   )
}

Answer 2

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

struct B {
    var id: String
}


struct C {
    var id: String
}

let aList: [A] = [A(id: "a", bId: "b", cId: "c")] // 100 elements

let bList: [B] = [B(id: "a")] // 200 elements

let cList: [C] = [C(id: "a")] // 300 elements

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
    }
}

var finalList: [FilterModel] = []
aList.forEach { a in
    let b = bList.first(where: { $0.id == a.id })
    let c = cList.first(where: { $0.id == a.id })
    finalList.append(FilterModel(objA: a, objB: b, objC: c))
}

如果记录是通过 API 传来的。我希望您对响应使用分页 使用紧凑型地图

 let finalList = aList.compactMap { a -> FilterModel in
        let b = bList.first(where: { $0.id == a.id })
        let c = cList.first(where: { $0.id == a.id })
        return FilterModel(objA: a, objB: b, objC: c)
    }