我过滤了字典的 NSMutableArray 然后我想再次过滤一个键

Question

var str = "Hello, playground"
var dataArray : NSMutableArray = []
var sum = 0.00

func addNewIncomeRecord(_ id: String, date: String, description: String, amount: Double, currency: String, category: String, notes: String) {
    let dict = ["id" : id, "date" : date, "description" : description, "amount" : amount, "currency" : currency, "category" : category, "notes" : notes] as [AnyHashable : Any]

    dataArray.add(dict)
}

addNewIncomeRecord("1", date: "11-25", description: "Money", amount: 20.00, currency: "EUR", category: "Home", notes: "More Money")
addNewIncomeRecord("2", date: "11-25", description: "Rent", amount: 50.00, currency: "EUR", category: "Home", notes: "Rent Money")
addNewIncomeRecord("3", date: "11-25", description: "Hair", amount: 10.00, currency: "EUR", category: "Medical"  ,notes: "HairCut")

let homeValue = NSPredicate(format: "category == %@", "Home")
let filteredArray = (dataArray as NSMutableArray).filtered(using: homeValue)
print(filteredArray)

我过滤了 "Home" 类别的所有数组。但现在我想再次过滤 filteredArray 的数量。这样只有两个（Home Arrays）的数量在一个额外的Array中。

Answer 1

不要在 Swift 中使用 NSArray 或 NSMutableArray。使用 Swift 本机数组（和字典）。
一旦你这样做了，就没有必要 NSPredicate。使用 filter 方法。
不要使用字典来保存数据。使用所需字段创建 struct。

首先，在不创建 struct 的情况下，这里有一个使用原生数组的简单解决方案：

var dataArray = [[String:Any]]()
var sum = 0.00

func addNewIncomeRecord(_ id: String, date: String, description: String, amount: Double, currency: String, category: String, notes: String) {
    let dict: [String:Any] = ["id" : id, "date" : date, "description" : description, "amount" : amount, "currency" : currency, "category" : category, "notes" : notes]

    dataArray.append(dict)
}

addNewIncomeRecord("1", date: "11-25", description: "Money", amount: 20.00, currency: "EUR", category: "Home", notes: "More Money")
addNewIncomeRecord("2", date: "11-25", description: "Rent", amount: 50.00, currency: "EUR", category: "Home", notes: "Rent Money")
addNewIncomeRecord("3", date: "11-25", description: "Hair", amount: 10.00, currency: "EUR", category: "Medical"  ,notes: "HairCut")

let filteredArray = dataArray.filter { [=10=]["category"] as? String == "Home" }
let amounts = filteredArray.flatMap { [=10=]["amount"] as? Double }
print(amounts)

这是使用 struct.

的解决方案

struct Income {
    let id: String
    let date: String
    let description: String
    let amount: Double
    let currency: String
    let category: String
    let notes: String
}

var dataArray = [Income]()
var sum = 0.00

func addNewIncomeRecord(_ id: String, date: String, description: String, amount: Double, currency: String, category: String, notes: String) {
    let income = Income(id: id, date: date, description: description, amount: amount, currency: currency, category: category, notes: notes)

    dataArray.append(income)
}

addNewIncomeRecord("1", date: "11-25", description: "Money", amount: 20.00, currency: "EUR", category: "Home", notes: "More Money")
addNewIncomeRecord("2", date: "11-25", description: "Rent", amount: 50.00, currency: "EUR", category: "Home", notes: "Rent Money")
addNewIncomeRecord("3", date: "11-25", description: "Hair", amount: 10.00, currency: "EUR", category: "Medical"  ,notes: "HairCut")

let filteredArray = dataArray.filter { [=11=].category == "Home" }
let amounts = filteredArray.map { [=11=].amount }
print(amounts)

使用 struct 有很多优点。它对每个字段都是类型安全的。您可以将其设置为 Codable，这样可以更轻松地保存和读取文件。

我过滤了字典的 NSMutableArray 然后我想再次过滤一个键

I filtered an NSMutableArray of Dictionaries and then I want to filter for a Key again

dictionary

filter

nsmutablearray

nspredicate

swift