Add support for currency selection

README.md

@@ -1,6 +1,6 @@
 # SatsPrice
 
-This app fetches the price of Bitcoin relative to the United States Dollar from multiple sources, and converts inputted amounts between Sats, BTC, and USD.
+This app fetches the price of Bitcoin relative to common ISO currencies from multiple sources, and converts inputted amounts between Sats, BTC, and the selected ISO currency.
 
 This is a free [Skip](https://skip.tools) dual-platform app project.
 It builds a native app for both iOS and Android.

Sources/SatsPrice/ContentView.swift

@@ -26,14 +26,14 @@ public struct ContentView: View {
     @MainActor
     func updatePrice() async {
         do {
-            guard let price = try await priceFetcherDelegator.btcToUsd() else {
+            guard let price = try await priceFetcherDelegator.convertBTC(toCurrency: satsViewModel.selectedCurrency) else {
-                satsViewModel.btcToUsdString = ""
+                satsViewModel.btcToCurrencyString = ""
                 return
             }
 
-            satsViewModel.btcToUsdString = "\(price)"
+            satsViewModel.btcToCurrencyString = "\(price)"
         } catch {
-            satsViewModel.btcToUsdString = ""
+            satsViewModel.btcToCurrencyString = ""
         }
         satsViewModel.lastUpdated = Date.now
     }
@@ -47,8 +47,18 @@ public struct ContentView: View {
                     }
                 }
 
+                Picker("Currency", selection: $satsViewModel.selectedCurrency) {
+                    ForEach(satsViewModel.currencies, id: \.self) {
+                        if let localizedCurrency = Locale.current.localizedString(forCurrencyCode: $0.identifier) {
+                            Text("\($0.identifier) - \(localizedCurrency)")
+                        } else {
+                            Text($0.identifier)
+                        }
+                    }
+                }
+
                 HStack {
-                    TextField("", text: $satsViewModel.btcToUsdString)
+                    TextField("", text: $satsViewModel.btcToCurrencyString)
                         .disabled(priceSource != .manual)
 #if os(iOS) || SKIP
                         .keyboardType(.decimalPad)
@@ -64,7 +74,7 @@ public struct ContentView: View {
                     }
                 }
             } header: {
-                Text("1 BTC to USD")
+                Text("1 BTC to \(satsViewModel.selectedCurrency.identifier)")
             } footer: {
                 if priceSource != .manual, let lastUpdated = satsViewModel.lastUpdated {
                     Text("Last updated: \(dateFormatter.string(from: lastUpdated))")
@@ -90,17 +100,23 @@ public struct ContentView: View {
             }
 
             Section {
-                TextField("", text: $satsViewModel.usdString)
+                TextField("", text: $satsViewModel.currencyValueString)
 #if os(iOS) || SKIP
                     .keyboardType(.decimalPad)
 #endif
             } header: {
-                Text("USD")
+                Text(satsViewModel.selectedCurrency.identifier)
             }
         }
         .task {
             await updatePrice()
         }
+        .onChange(of: satsViewModel.selectedCurrency) { newCurrency in
+            satsViewModel.lastUpdated = nil
+            Task {
+                await updatePrice()
+            }
+        }
         .onChange(of: priceSource) { newPriceSource in
             satsViewModel.lastUpdated = nil
             priceFetcherDelegator.priceSource = newPriceSource

Sources/SatsPrice/Network/CoinGeckoPriceFetcher.swift

@@ -11,35 +11,35 @@
 import Foundation
 
 private struct CoinGeckoPriceResponse: Codable {
-    let bitcoin: CoinGeckoPrice
-}
-
-private struct CoinGeckoPrice: Codable {
 #if !SKIP
-    let usd: Decimal
+    let bitcoin: [String: Decimal]
 #else
-    let usd: String
+    let bitcoin: [String: String]
 #endif
 }
 
 class CoinGeckoPriceFetcher : PriceFetcher {
-    private static let urlString = "https://api.coingecko.com/api/v3/simple/price?ids=bitcoin&vs_currencies=usd&precision=18"
+    func urlString(toCurrency currency: Locale.Currency) -> String {
+        "https://api.coingecko.com/api/v3/simple/price?ids=bitcoin&vs_currencies=\(currency.identifier.lowercased())&precision=18"
+    }
 
-    func btcToUsd() async throws -> Decimal? {
+    func convertBTC(toCurrency currency: Locale.Currency) async throws -> Decimal? {
         do {
-            guard let urlComponents = URLComponents(string: CoinGeckoPriceFetcher.urlString), let url = urlComponents.url else {
+            guard let urlComponents = URLComponents(string: urlString(toCurrency: currency)), let url = urlComponents.url else {
                 return nil
             }
 
             let (data, _) = try await URLSession.shared.data(from: url, delegate: nil)
 
             let priceResponse = try JSONDecoder().decode(CoinGeckoPriceResponse.self, from: data)
-            let price = priceResponse.bitcoin
+            guard let price = priceResponse.bitcoin[currency.identifier.lowercased()] else {
+                return nil
+            }
 
 #if !SKIP
-            return price.usd
+            return price
 #else
-            return Decimal(price.usd)
+            return Decimal(price)
 #endif
         } catch {
             return nil

Sources/SatsPrice/Network/CoinbasePriceFetcher.swift

@@ -21,13 +21,13 @@ private struct CoinbasePrice: Codable {
 }
 
 class CoinbasePriceFetcher : PriceFetcher {
-    private static let urlString = "https://api.coinbase.com/v2/prices/BTC-USD/spot"
+    func urlString(toCurrency currency: Locale.Currency) -> String {
-    private static let btc = "BTC"
+        "https://api.coinbase.com/v2/prices/BTC-\(currency.identifier)/spot"
-    private static let usd = "USD"
+    }
 
-    func btcToUsd() async throws -> Decimal? {
+    func convertBTC(toCurrency currency: Locale.Currency) async throws -> Decimal? {
         do {
-            guard let urlComponents = URLComponents(string: CoinbasePriceFetcher.urlString), let url = urlComponents.url else {
+            guard let urlComponents = URLComponents(string: urlString(toCurrency: currency)), let url = urlComponents.url else {
                 return nil
             }
 
@@ -36,7 +36,7 @@ class CoinbasePriceFetcher : PriceFetcher {
             let coinbasePriceResponse = try JSONDecoder().decode(CoinbasePriceResponse.self, from: data)
             let coinbasePrice = coinbasePriceResponse.data
 
-            guard coinbasePrice.base == CoinbasePriceFetcher.btc && coinbasePrice.currency == CoinbasePriceFetcher.usd else {
+            guard coinbasePrice.base == "BTC" && coinbasePrice.currency == currency.identifier else {
                 return nil
             }
 

Sources/SatsPrice/Network/FakePriceFetcher.swift

@@ -13,7 +13,7 @@ import Foundation
 
 /// Fake price fetcher that returns a randomized price. Useful for development testing without requiring a network call.
 class FakePriceFetcher: PriceFetcher {
-    func btcToUsd() async throws -> Decimal? {
+    func convertBTC(toCurrency currency: Locale.Currency) async throws -> Decimal? {
         Decimal(Double.random(in: 10000...100000))
     }
 }

Sources/SatsPrice/Network/ManualPriceFetcher.swift

@@ -14,7 +14,7 @@ import Foundation
 class ManualPriceFetcher: PriceFetcher {
     var price: Decimal = Decimal(1)
 
-    func btcToUsd() async throws -> Decimal? {
+    func convertBTC(toCurrency currency: Locale.Currency) async throws -> Decimal? {
         return price
     }
 }

Sources/SatsPrice/Network/PriceFetcher.swift

@@ -11,5 +11,5 @@
 import Foundation
 
 protocol PriceFetcher {
-    func btcToUsd() async throws -> Decimal?
+    func convertBTC(toCurrency currency: Locale.Currency) async throws -> Decimal?
 }

Sources/SatsPrice/Network/PriceFetcherDelegator.swift

@@ -39,7 +39,7 @@ class PriceFetcherDelegator: PriceFetcher {
         }
     }
 
-    func btcToUsd() async throws -> Decimal? {
+    func convertBTC(toCurrency currency: Locale.Currency) async throws -> Decimal? {
-        return try await delegate.btcToUsd()
+        return try await delegate.convertBTC(toCurrency: currency)
     }
 }

Sources/SatsPrice/Resources/Localizable.xcstrings

@@ -4,11 +4,24 @@
     "" : {
 
     },
-    "1 BTC to USD" : {
+    "%@ - %@" : {
+      "localizations" : {
+        "en" : {
+          "stringUnit" : {
+            "state" : "new",
+            "value" : "%1$@ - %2$@"
+          }
+        }
+      }
+    },
+    "1 BTC to %@" : {
 
     },
     "BTC" : {
 
+    },
+    "Currency" : {
+
     },
     "Last updated: %@" : {
 
@@ -18,9 +31,6 @@
     },
     "Sats" : {
 
-    },
-    "USD" : {
-
     }
   },
   "version" : "1.0"

Sources/SatsPrice/SatsViewModel.swift

@@ -15,26 +15,40 @@ import SwiftUI
 class SatsViewModel: ObservableObject {
     @Published var lastUpdated: Date?
 
-    @Published var btcToUsdStringInternal: String = ""
+    @Published var btcToCurrencyStringInternal: String = ""
     @Published var satsStringInternal: String = ""
     @Published var btcStringInternal: String = ""
-    @Published var usdStringInternal: String = ""
+    @Published var currencyValueStringInternal: String = ""
+    @Published var selectedCurrency: Locale.Currency = Locale.current.currency ?? Locale.Currency("USD")
 
-    var btcToUsdString: String {
+    var currencies: [Locale.Currency] {
+        let commonISOCurrencyCodes = Set(Locale.commonISOCurrencyCodes)
+        let currentCurrency = Locale.current.currency ?? Locale.Currency("USD")
+        if commonISOCurrencyCodes.contains(currentCurrency.identifier) {
+            return Locale.commonISOCurrencyCodes.map { Locale.Currency($0) }
+        } else {
+            var commonAndCurrentCurrencies = Locale.commonISOCurrencyCodes
+            commonAndCurrentCurrencies.append(currentCurrency.identifier)
+            commonAndCurrentCurrencies.sort()
+            return commonAndCurrentCurrencies.map { Locale.Currency($0) }
+        }
+    }
+
+    var btcToCurrencyString: String {
         get {
-            btcToUsdStringInternal
+            btcToCurrencyStringInternal
         }
         set {
-            guard btcToUsdStringInternal != newValue else {
+            guard btcToCurrencyStringInternal != newValue else {
                 return
             }
 
-            btcToUsdStringInternal = newValue
+            btcToCurrencyStringInternal = newValue
 
-            if let btc, let btcToUsd {
+            if let btc, let btcToCurrency {
-                usdStringInternal = (btc * btcToUsd).formatString()
+                currencyValueStringInternal = (btc * btcToCurrency).formatString()
             } else {
-                usdStringInternal = ""
+                currencyValueStringInternal = ""
             }
         }
     }
@@ -57,14 +71,14 @@ class SatsViewModel: ObservableObject {
                 let btc = sats.divide(Decimal(100000000), 20, java.math.RoundingMode.DOWN)
 #endif
                 btcStringInternal = btc.formatString()
-                if let btcToUsd {
+                if let btcToCurrency {
-                    usdStringInternal = (btc * btcToUsd).formatString()
+                    currencyValueStringInternal = (btc * btcToCurrency).formatString()
                 } else {
-                    usdStringInternal = ""
+                    currencyValueStringInternal = ""
                 }
             } else {
                 btcStringInternal = ""
-                usdStringInternal = ""
+                currencyValueStringInternal = ""
             }
         }
     }
@@ -84,35 +98,35 @@ class SatsViewModel: ObservableObject {
                 let sats = btc * Decimal(100000000)
                 satsStringInternal = sats.formatString()
 
-                if let btcToUsd {
+                if let btcToCurrency {
-                    usdStringInternal = (btc * btcToUsd).formatString()
+                    currencyValueStringInternal = (btc * btcToCurrency).formatString()
                 } else {
-                    usdStringInternal = ""
+                    currencyValueStringInternal = ""
                 }
             } else {
                 satsStringInternal = ""
-                usdStringInternal = ""
+                currencyValueStringInternal = ""
             }
         }
     }
 
-    var usdString: String {
+    var currencyValueString: String {
         get {
-            usdStringInternal
+            currencyValueStringInternal
         }
         set {
-            guard usdStringInternal != newValue else {
+            guard currencyValueStringInternal != newValue else {
                 return
             }
 
-            usdStringInternal = newValue
+            currencyValueStringInternal = newValue
 
-            if let usd {
+            if let currencyValue {
-                if let btcToUsd {
+                if let btcToCurrency {
 #if !SKIP
-                    let btc = usd / btcToUsd
+                    let btc = currencyValue / btcToCurrency
 #else
-                    let btc = usd.divide(btcToUsd, 20, java.math.RoundingMode.DOWN)
+                    let btc = currencyValue.divide(btcToCurrency, 20, java.math.RoundingMode.DOWN)
 #endif
                     btcStringInternal = btc.formatString()
 
@@ -120,21 +134,21 @@ class SatsViewModel: ObservableObject {
                     satsStringInternal = sats.formatString()
                 } else {
                     satsStringInternal = ""
-                    usdStringInternal = ""
+                    currencyValueStringInternal = ""
                 }
             } else {
                 satsStringInternal = ""
-                usdStringInternal = ""
+                currencyValueStringInternal = ""
             }
         }
     }
 
-    var btcToUsd: Decimal? {
+    var btcToCurrency: Decimal? {
 #if !SKIP
-        return Decimal(string: btcToUsdStringInternal)
+        return Decimal(string: btcToCurrencyStringInternal)
 #else
         do {
-            return Decimal(btcToUsdStringInternal)
+            return Decimal(btcToCurrencyStringInternal)
         } catch {
             return nil
         }
@@ -165,12 +179,12 @@ class SatsViewModel: ObservableObject {
 #endif
     }
 
-    var usd: Decimal? {
+    var currencyValue: Decimal? {
 #if !SKIP
-        return Decimal(string: usdStringInternal)
+        return Decimal(string: currencyValueStringInternal)
 #else
         do {
-            return Decimal(usdStringInternal)
+            return Decimal(currencyValueStringInternal)
         } catch {
             return nil
         }

Tests/SatsPriceTests/SatsViewModelTests.swift

@@ -8,6 +8,7 @@
 //  Created by Terry Yiu on 2/19/24.
 //
 
+import Foundation
 import XCTest
 @testable import SatsPrice
 
@@ -15,52 +16,88 @@ final class SatsViewModelTests: XCTestCase {
 
     func testSatsViewModel() {
         let satsViewModel = SatsViewModel()
-        satsViewModel.btcToUsdString = "54321"
+        satsViewModel.btcToCurrencyString = "54321"
 
         // Test BTC updates.
         satsViewModel.btcString = "1"
+#if !SKIP
         XCTAssertEqual(satsViewModel.btc, Decimal(string: "1"))
-        XCTAssertEqual(satsViewModel.btcString, "1")
         XCTAssertEqual(satsViewModel.sats, Decimal(string: "100000000"))
+        XCTAssertEqual(satsViewModel.currencyValue, Decimal(string: "54321"))
+#else
+        XCTAssertEqual(satsViewModel.btc, Decimal("1"))
+        XCTAssertEqual(satsViewModel.sats, Decimal("100000000"))
+        XCTAssertEqual(satsViewModel.currencyValue, Decimal("54321"))
+#endif
+        XCTAssertEqual(satsViewModel.btcString, "1")
         XCTAssertEqual(satsViewModel.satsString, "100000000")
-        XCTAssertEqual(satsViewModel.usd, Decimal(string: "54321"))
+        XCTAssertEqual(satsViewModel.currencyValueString, "54321")
-        XCTAssertEqual(satsViewModel.usdString, "54321")
 
         // Test Sats updates.
         satsViewModel.satsString = "200000000"
+#if !SKIP
         XCTAssertEqual(satsViewModel.btc, Decimal(string: "2"))
-        XCTAssertEqual(satsViewModel.btcString, "2")
         XCTAssertEqual(satsViewModel.sats, Decimal(string: "200000000"))
+        XCTAssertEqual(satsViewModel.currencyValue, Decimal(string: "108642"))
+#else
+        XCTAssertEqual(satsViewModel.btc, Decimal("2"))
+        XCTAssertEqual(satsViewModel.sats, Decimal("200000000"))
+        XCTAssertEqual(satsViewModel.currencyValue, Decimal("108642"))
+#endif
+        XCTAssertEqual(satsViewModel.btcString, "2")
         XCTAssertEqual(satsViewModel.satsString, "200000000")
-        XCTAssertEqual(satsViewModel.usd, Decimal(string: "108642"))
+        XCTAssertEqual(satsViewModel.currencyValueString, "108642")
-        XCTAssertEqual(satsViewModel.usdString, "108642")
 
-        // Test USD updates.
+        // Test currency value updates.
-        satsViewModel.usdString = "162963"
+        satsViewModel.currencyValueString = "162963"
+#if !SKIP
         XCTAssertEqual(satsViewModel.btc, Decimal(string: "3"))
-        XCTAssertEqual(satsViewModel.btcString, "3")
         XCTAssertEqual(satsViewModel.sats, Decimal(string: "300000000"))
+        XCTAssertEqual(satsViewModel.currencyValue, Decimal(string: "162963"))
+#else
+        XCTAssertEqual(satsViewModel.btc, Decimal("3"))
+        XCTAssertEqual(satsViewModel.sats, Decimal("300000000"))
+        XCTAssertEqual(satsViewModel.currencyValue, Decimal("162963"))
+#endif
+        XCTAssertEqual(satsViewModel.btcString, "3")
         XCTAssertEqual(satsViewModel.satsString, "300000000")
-        XCTAssertEqual(satsViewModel.usd, Decimal(string: "162963"))
+        XCTAssertEqual(satsViewModel.currencyValueString, "162963")
-        XCTAssertEqual(satsViewModel.usdString, "162963")
 
         // Test fractional amounts.
-        satsViewModel.usdString = "1"
+        // Precision between platforms on this calculation is different so we have different assertions for each.
+        satsViewModel.currencyValueString = "1"
+#if !SKIP
         XCTAssertEqual(satsViewModel.btc, Decimal(string: "0.00001840908672520756245282671526665562"))
         XCTAssertEqual(satsViewModel.btcString, "0.00001840908672520756245282671526665562")
         XCTAssertEqual(satsViewModel.sats, Decimal(string: "1840.908672520756245282671526665562"))
         XCTAssertEqual(satsViewModel.satsString, "1840.908672520756245282671526665562")
-        XCTAssertEqual(satsViewModel.usd, Decimal(string: "1"))
+        XCTAssertEqual(satsViewModel.currencyValue, Decimal(string: "1"))
-        XCTAssertEqual(satsViewModel.usdString, "1")
+#else
+        XCTAssertEqual(satsViewModel.btc, Decimal("0.00001840908672520756"))
+        XCTAssertEqual(satsViewModel.btcString, "0.00001840908672520756")
+        XCTAssertEqual(satsViewModel.sats, Decimal("1840.908672520756"))
+        XCTAssertEqual(satsViewModel.satsString, "1840.908672520756")
+        XCTAssertEqual(satsViewModel.currencyValue, Decimal("1"))
+#endif
+        XCTAssertEqual(satsViewModel.currencyValueString, "1")
 
         // Test large amounts that exceed the cap of 21M BTC.
-        satsViewModel.usdString = "11407419999999"
+        // Precision between platforms on this calculation is different so we have different assertions for each.
+        satsViewModel.currencyValueString = "11407419999999"
+#if !SKIP
         XCTAssertEqual(satsViewModel.btc, Decimal(string: "210000184.09084884298889932070469983984"))
         XCTAssertEqual(satsViewModel.btcString, "210000184.09084884298889932070469983984")
         XCTAssertEqual(satsViewModel.sats, Decimal(string: "21000018409084884.298889932070469983984"))
         XCTAssertEqual(satsViewModel.satsString, "21000018409084884.298889932070469983984")
-        XCTAssertEqual(satsViewModel.usd, Decimal(string: "11407419999999"))
+        XCTAssertEqual(satsViewModel.currencyValue, Decimal(string: "11407419999999"))
-        XCTAssertEqual(satsViewModel.usdString, "11407419999999")
+#else
+        XCTAssertEqual(satsViewModel.btc, Decimal("210000184.0908488429888993207"))
+        XCTAssertEqual(satsViewModel.btcString, "210000184.0908488429888993207")
+        XCTAssertEqual(satsViewModel.sats, Decimal("21000018409084884.29888993207"))
+        XCTAssertEqual(satsViewModel.satsString, "21000018409084884.29888993207")
+        XCTAssertEqual(satsViewModel.currencyValue, Decimal("11407419999999"))
+#endif
+        XCTAssertEqual(satsViewModel.currencyValueString, "11407419999999")
     }
 
 }