Add nonce & timestamp to block

Sources/Blockchain/Models/Block.swift

@@ -10,12 +10,27 @@ import Foundation
 import CryptoSwift
 
 class Block {
-    var hash: String!
-    var data: String!
-    var previousHash: String!
-    var index: Int!
+    var hash: String
+    var data: String
+    var previousHash: String
+    var index: Int
+    var nonce: Int
+    var timestamp: Int
+    
+    init(hash: String = "", data: String = "", previousHash: String = "", index: Int = 0, nonce: Int = 0, timestamp: Int = 0) {
+        self.data = data
+        self.previousHash = previousHash
+        self.index = index
+        self.nonce = nonce
+        self.timestamp = timestamp
+        self.hash = hash
+    }
     
     func generateHash() -> String {
         return data.sha256()
     }
+    
+    func generateTimestamp() -> Int {
+        return Int(Date().timeIntervalSince1970)
+    }
 }