Creating a Coin Model based on JSON response from an API | SwiftUI Crypto App #3

CryptoApp: Data Modeling

구현 목표

• API 리턴하는 JSON 구조에 따른 구조체 모델링

구현 태스크

• API 리턴 값 확인
• 코딩 키 생성
• Codable 프로토콜 사용
• 연산 프로퍼티 활용

핵심 코드

import Foundation

struct CoinModel: Codable, Identifiable {
    let id, symbol, name: String
    let image: String
    let currentPrice: Double
    let marketCap, marketCapRank: Double?
    let fullyDilutedValuation: Double?
    let totalVolume, high24H, low24H, priceChange24H: Double?
    let priceChangePercentage24H, marketCapChange24H, marketCapChangePercentage24H, circulatingSupply: Double?
    let totalSupply, maxSupply: Double?
    let ath, athChangePercentage: Double?
    let athDate: String?
    let atl, atlChangePercentage: Double?
    let atlDate: String?
    let lastUpdated: String?
    let sparklineIn7D: SparklineIn7D?
    let priceChangePercentage24HInCurrency: Double?
    let currentHoldings: Double?
    
    enum CodingKeys: String, CodingKey {
        case id, symbol, name, image
        case currentPrice = "current_price"
        case marketCap = "market_cap"
        case marketCapRank = "market_cap_rank"
        case fullyDilutedValuation = "fully_diluted_valuation"
        case totalVolume = "total_volume"
        case high24H = "high_24h"
        case low24H = "low_24h"
        case priceChange24H = "price_change_24h"
        case priceChangePercentage24H = "price_change_percentage_24h"
        case marketCapChange24H = "market_cap_change_24h"
        case marketCapChangePercentage24H = "market_cap_change_percentage_24h"
        case circulatingSupply = "circulating_supply"
        case totalSupply = "total_supply"
        case maxSupply = "max_supply"
        case ath
        case athChangePercentage = "ath_change_percentage"
        case athDate = "ath_date"
        case atl
        case atlChangePercentage = "atl_change_percentage"
        case atlDate = "atl_date"
        case lastUpdated = "last_updated"
        case sparklineIn7D = "sparkline_in_7d"
        case priceChangePercentage24HInCurrency = "price_change_percentage_24h_in_currency"
        case currentHoldings
    }
    
    func updateHoldings(amount: Double) -> CoinModel {
        return CoinModel(id: id, symbol: symbol, name: name, image: image, currentPrice: currentPrice, marketCap: marketCap, marketCapRank: marketCapRank, fullyDilutedValuation: fullyDilutedValuation, totalVolume: totalVolume, high24H: high24H, low24H: low24H, priceChange24H: priceChange24H, priceChangePercentage24H: priceChangePercentage24H, marketCapChange24H: marketCapChange24H, marketCapChangePercentage24H: marketCapChangePercentage24H, circulatingSupply: circulatingSupply, totalSupply: totalSupply, maxSupply: maxSupply, ath: ath, athChangePercentage: athChangePercentage, athDate: athDate, atl: atl, atlChangePercentage: atlChangePercentage, atlDate: atlDate, lastUpdated: lastUpdated, sparklineIn7D: sparklineIn7D, priceChangePercentage24HInCurrency: priceChangePercentage24HInCurrency, currentHoldings: currentHoldings)
    }
    
    var currentHoldingsValue: Double {
        return (currentHoldings ?? 0) * currentPrice
    }
    
    var rank: Int {
        return Int(marketCapRank ?? 0)
    }
}

• 리턴받은 값을 통해 updateHoldings, currentHoldingsValue 등 함수 및 연산 프로퍼티 구현 가능
• 코딩 키를 통해 json 디코딩 시 구조체 변수명에 맞게 매칭 가능