From 74d541d8da74837c14416fae1cd81cff667ce0f7 Mon Sep 17 00:00:00 2001
From: James Sangalli <j.l.sangalli@gmail.com>
Date: Sun, 5 Jan 2020 16:14:30 +0800
Subject: [PATCH] clean up force unwraps

---
 .../Coordinators/UniversalLinkCoordinator.swift       |  4 +---
 AlphaWallet/Redeem/Helpers/CreateRedeem.swift         |  6 +++---
 AlphaWallet/Redeem/Helpers/SignatureHelper.swift      | 11 ++++++-----
 .../TokenCardRedemptionViewController.swift           | 10 +++++++---
 4 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/AlphaWallet/Market/Coordinators/UniversalLinkCoordinator.swift b/AlphaWallet/Market/Coordinators/UniversalLinkCoordinator.swift
index f0a5c5af2..6e6526061 100644
--- a/AlphaWallet/Market/Coordinators/UniversalLinkCoordinator.swift
+++ b/AlphaWallet/Market/Coordinators/UniversalLinkCoordinator.swift
@@ -609,9 +609,7 @@ class UniversalLinkCoordinator: Coordinator {
     }
 
     private func convert(ethCost: BigUInt) -> Decimal {
-        //TODO extract constant. Used elsewhere too
-        let divideAmount = Decimal(string: "1000000000000000000")!
-        let etherCostDecimal = Decimal(string: ethCost.description)! / divideAmount
+        let etherCostDecimal = Decimal(string: ethCost.description)! /  Decimal(EthereumUnit.ether.rawValue)
         return etherCostDecimal
     }
 }
diff --git a/AlphaWallet/Redeem/Helpers/CreateRedeem.swift b/AlphaWallet/Redeem/Helpers/CreateRedeem.swift
index 0723ed34b..994bc6237 100644
--- a/AlphaWallet/Redeem/Helpers/CreateRedeem.swift
+++ b/AlphaWallet/Redeem/Helpers/CreateRedeem.swift
@@ -64,10 +64,10 @@ class CreateRedeem {
         /* the method here is easier to express with matrix programming like this:
         indexList = indexList - correctionFactor # reduce every element of the list by an int
         selection = sum(2^indexList)             # raise every element and add the result back */
-        var bitFieldLookup = BigUInt("0")!
+        var bitFieldLookup = BigUInt(0)
         for _ in 0...indices.count - 1 {
-            let adder = BigUInt("2")?.power(Int(indices[0]) - correctionFactor)
-            bitFieldLookup = bitFieldLookup.advanced(by: BigInt(adder!))
+            let adder = BigUInt(2).power(Int(indices[0]) - correctionFactor)
+            bitFieldLookup = bitFieldLookup.advanced(by: BigInt(adder))
         }
 
         let bitIntLength: Int = bitFieldLookup.description.count
diff --git a/AlphaWallet/Redeem/Helpers/SignatureHelper.swift b/AlphaWallet/Redeem/Helpers/SignatureHelper.swift
index 4d3523ea5..61edcf0f5 100644
--- a/AlphaWallet/Redeem/Helpers/SignatureHelper.swift
+++ b/AlphaWallet/Redeem/Helpers/SignatureHelper.swift
@@ -10,8 +10,8 @@ import Foundation
 import BigInt
 
 class SignatureHelper {
-    class func signatureAsHex(for message: String, account: EthereumAccount) -> String? {
-        let keystore = try! EtherKeystore()
+    class func signatureAsHex(for message: String, account: EthereumAccount) throws -> String? {
+        let keystore = try EtherKeystore()
         let signature = keystore.signMessageData(message.data(using: String.Encoding.utf8), for: account)
         let signatureHex = try? signature.dematerialize().hex(options: .upperCase)
         guard let data = signatureHex else {
@@ -20,8 +20,9 @@ class SignatureHelper {
         return data
     }
 
-    class func signatureAsDecimal(for message: String, account: EthereumAccount) -> String? {
-        let signatureHex = signatureAsHex(for: message, account: account)!
-        return BigInt(signatureHex, radix: 16)!.description
+    class func signatureAsDecimal(for message: String, account: EthereumAccount) throws -> String? {
+        guard let signatureHex = try signatureAsHex(for: message, account: account) else { return nil }
+        guard let signatureDecimalString = BigInt(signatureHex, radix: 16)?.description else { return nil }
+        return signatureDecimalString
     }
 }
diff --git a/AlphaWallet/Redeem/ViewControllers/TokenCardRedemptionViewController.swift b/AlphaWallet/Redeem/ViewControllers/TokenCardRedemptionViewController.swift
index a1d6c5585..4adcc48b4 100644
--- a/AlphaWallet/Redeem/ViewControllers/TokenCardRedemptionViewController.swift
+++ b/AlphaWallet/Redeem/ViewControllers/TokenCardRedemptionViewController.swift
@@ -114,9 +114,13 @@ class TokenCardRedemptionViewController: UIViewController, TokenVerifiableStatus
         }
         switch session.account.type {
         case .real(let account):
-            let decimalSignature = SignatureHelper.signatureAsDecimal(for: redeemData.message, account: account)!
-            let qrCodeInfo = redeemData.qrCode + decimalSignature
-            imageView.image = qrCodeInfo.toQRCode()
+            do {
+                guard let decimalSignature = try SignatureHelper.signatureAsDecimal(for: redeemData.message, account: account) else { break }
+                let qrCodeInfo = redeemData.qrCode + decimalSignature
+                imageView.image = qrCodeInfo.toQRCode()
+            } catch {
+                break
+            }
         case .watch: break
         }
     }