Restrict the length of verify code.

Yep/ViewControllers/Login/LoginVerifyMobileViewController.swift

@@ -231,5 +231,14 @@ extension LoginVerifyMobileViewController: UITextFieldDelegate {
         return true
     }
     */
+
+    func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
+        let currentCharacterCount = textField.text?.characters.count ?? 0
+        if range.length + range.location > currentCharacterCount {
+            return false
+        }
+        let newLength = currentCharacterCount + string.characters.count - range.length
+        return newLength <= YepConfig.verifyCodeLength()
+    }
 }
 

Yep/ViewControllers/Register/RegisterVerifyMobileViewController.swift

@@ -225,5 +225,14 @@ extension RegisterVerifyMobileViewController: UITextFieldDelegate {
         return true
     }
     */
+
+    func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
+        let currentCharacterCount = textField.text?.characters.count ?? 0
+        if range.length + range.location > currentCharacterCount {
+            return false
+        }
+        let newLength = currentCharacterCount + string.characters.count - range.length
+        return newLength <= YepConfig.verifyCodeLength()
+    }
 }