Fix: migration to fix DAI token wrongly marked as decimals=0 when it's tagged as ERC721

AlphaWallet/Core/Initializers/MigrationInitializer.swift

@@ -15,7 +15,7 @@ class MigrationInitializer: Initializer {
     }
 
     func perform() {
-        config.schemaVersion = 4
+        config.schemaVersion = 5
         config.migrationBlock = { migration, oldSchemaVersion in
             if oldSchemaVersion < 2 {
                 //Fix bug created during multi-chain implementation. Where TokenObject instances are created from transfer Transaction instances, with the primaryKey as a empty string; so instead of updating an existing TokenObject, a duplicate TokenObject instead was created but with primaryKey empty
@@ -49,5 +49,16 @@ class MigrationInitializer: Initializer {
                 }
             }
         }
+        config.migrationBlock = { migration, oldSchemaVersion in
+            if oldSchemaVersion < 5 {
+                migration.enumerateObjects(ofType: TokenObject.className()) { oldObject, newObject in
+                    guard let oldObject = oldObject else { return }
+                    guard let newObject = newObject else { return }
+                    //Fix bug introduced when OpenSea suddenly includes the DAI stablecoin token in their results with an existing versioned API endpoint, and we wrongly tagged it as ERC721 with decimals=0. The earlier migration (version=4) only set the type back to ERC20, but the decimals remained as 0
+                    guard let contract = oldObject["contract"] as? String, contract == "0x89d24A6b4CcB1B6fAA2625fE562bDD9a23260359" else { return }
+                    newObject["decimals"] = 18
+                }
+            }
+        }
     }
 }