TF-2871 Fix validate expire time in swift code

ios/TwakeCore/Extensions/DateExtensions.swift

@@ -4,4 +4,11 @@ extension Date {
     func isBefore(_ otherDate: Date) -> Bool {
         return self < otherDate
     }
+    
+    func convertDateToISO8601String() -> String {
+        let dateFormatter = DateFormatter()
+        dateFormatter.dateFormat = CoreUtils.ISO8601_DATE_FORMAT
+        dateFormatter.locale = Locale(identifier: CoreUtils.EN_US_POSIX_LOCALE)
+        return dateFormatter.string(from: self)
+    }
 }

ios/TwakeCore/Extensions/IntegerExtensions.swift

@@ -0,0 +1,11 @@
+import Foundation
+
+extension Int {
+    func convertMillisecondsToDate() -> Date {
+        return Date(timeIntervalSince1970: TimeInterval(self) / 1000)
+    }
+    
+    func convertMillisecondsToISO8601String() -> String {
+        return convertMillisecondsToDate().convertDateToISO8601String()
+    }
+}

ios/TwakeCore/Extensions/StringExtensions.swift

@@ -3,8 +3,8 @@ import Foundation
 extension String {
     func convertISO8601StringToDate() -> Date? {
         let dateFormatter = DateFormatter()
-        dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSS"
-        dateFormatter.locale = Locale(identifier: "en_US_POSIX")
+        dateFormatter.dateFormat = CoreUtils.ISO8601_DATE_FORMAT
+        dateFormatter.locale = Locale(identifier: CoreUtils.EN_US_POSIX_LOCALE)
         return dateFormatter.date(from: self)
     }