Create a comparison in an array - ios

Question

I working on an app to show some information about cities
In an array I have two parameters
1- languages (I don't know how many there are)
2- the number of people that speak on that language
I get this data from an server
here is this two paramter in JSon
"language": "French",
"number": "12321",
these data among other data is saved in an array
I Just want to get the most used language with the pecentage
for example French with 35%
how can I do it in swift?
Your help will be appreciated.

Answer 1

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:
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
count the sum of all users (you can do it using for loop or reduce like in my example)
sort your list, so the language with the most users will be first
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.

Answer 2

The simplest way is:
// Example JSON
const exampleJSON = {
"people": [
{
"language": "French",
"number": 12321,
},
{
"language": "English",
"number": 7000,
}
]
};
// Parse it
const parsed = JSON.parse(JSON.stringify(exampleJSON));
const speakers = [...parsed.people];
// Count number of all speakers and let it be as 100%
let sumAllSpeakers = 0;
parsed.people.reduce((previous, current) => {
sumAllSpeakers = previous.number + current.number;
return previous;
});
// Compare fucntion
const compareSpeakers = (speaker1, speaker2) => {
if (speaker1.number > speaker2.number) {
return -1;
}
if (speaker1.number < speaker2.number) {
return 1;
}
return 0;
}
// Create new array with statistic sorted from max number
const statisticsOfSpeakersInPersent = speakers
.sort((speaker1, speaker2) => compareSpeakers(speaker1, speaker2))
.map(speaker => {
return {...speaker, ...{inPersent: speaker.number * 100 / sumAllSpeakers + '%'}}
});
I hope this example helps you.
Out:
[ { language: 'French',
number: 12321,
inPersent: '63.76999120128358%' }, { language: 'English',
number: 7000,
inPersent: '36.23000879871642%' } ]