[Solved] Create a comparison in an array

by 


import Foundation

let serverOutput = Data("""
[
    {
        "language": "French",
        "number": "12"
    },
    {
        "language": "English",
        "number": "10"
    }
]
""".utf8)

struct LangueUsers: Codable {
    let language: String
    let number: Int

    enum CodingKeys: CodingKey {
        case language
        case number
    }

    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        language = try container.decode(String.self, forKey: .language)
        let rawNumber = try container.decode(String.self, forKey: .number)
        guard let number = Int(rawNumber) else {
            throw DecodingError.typeMismatch(Int.self, DecodingError.Context(codingPath: [CodingKeys.number], debugDescription: "\(rawNumber) can't be convert to Int"))
        }
        self.number = number
    }
}

struct LangueUsersPercent: CustomStringConvertible {
    let language: String
    let share: Double

    init(language: String, number: Int, all: Int) {
        self.language = language
        self.share = Double(number) / Double(all)
    }

    var description: String {
        return String(format: "%@ - %0.1f%%", language, share * 100)
    }
}

let decoder = JSONDecoder()
//1
var output = try decoder.decode([LangueUsers].self, from: serverOutput)
//2
let allUser = output.reduce(0) { (reult, languageUsers) -> Int in
    reult + Int(languageUsers.number)
}
//3
output.sort { (lhs, rhs) -> Bool in
    lhs.number > rhs.number
}
//4
let response = output.map {
    LangueUsersPercent(language: $0.language, number: $0.number, all: allUser)
}
print(response[0])

The code assumes that the output from a server is in serverOutput variable. So steps need to achieve your task:

  1. decode your JSON to swift structure (called LangueUsers) using swift codable. Keep in mind that by default it won’t convert string values to int, so I have to create a custom init(from decoder: Decoder) initializer
  2. count the sum of all users (you can do it using for loop or reduce like in my example)
  3. sort your list, so the language with the most users will be first
  4. this step is optional, but I’ve added a separate structure that will help us generate output and in this step, we are rewriting our input structures to output ones

Hope this is clear for you. Let me know if you have any questions.

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solved Create a comparison in an array