diff --git a/.ruby-version b/.ruby-version
index 5859406..005119b 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-2.2.3
+2.4.1
diff --git a/Examples/TAKUUIDSample.xcodeproj/project.pbxproj b/Examples/TAKUUIDSample.xcodeproj/project.pbxproj
index 01135ac..7d2c6aa 100644
--- a/Examples/TAKUUIDSample.xcodeproj/project.pbxproj
+++ b/Examples/TAKUUIDSample.xcodeproj/project.pbxproj
@@ -308,7 +308,7 @@
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 			shellPath = /bin/sh;
-			shellScript = "diff \"${PODS_ROOT}/../Podfile.lock\" \"${PODS_ROOT}/Manifest.lock\" > /dev/null\nif [ $? != 0 ] ; then\n    # print error to STDERR\n    echo \"error: The sandbox is not in sync with the Podfile.lock. Run 'pod install' or update your CocoaPods installation.\" >&2\n    exit 1\nfi\n";
+			shellScript = "diff \"${PODS_PODFILE_DIR_PATH}/Podfile.lock\" \"${PODS_ROOT}/Manifest.lock\" > /dev/null\nif [ $? != 0 ] ; then\n    # print error to STDERR\n    echo \"error: The sandbox is not in sync with the Podfile.lock. Run 'pod install' or update your CocoaPods installation.\" >&2\n    exit 1\nfi\n";
 			showEnvVarsInLog = 0;
 		};
 		6DBF134E89C83603FBA41475 /* [CP] Copy Pods Resources */ = {
diff --git a/Examples/TAKUUIDSample/TAKViewController.swift b/Examples/TAKUUIDSample/TAKViewController.swift
index 1d7eb63..56ac01e 100644
--- a/Examples/TAKUUIDSample/TAKViewController.swift
+++ b/Examples/TAKUUIDSample/TAKViewController.swift
@@ -21,13 +21,13 @@ final class TAKViewController: UIViewController {
   }
   
   @IBAction func findOrCreate() {
-    let uuid = TAKUUIDStorage.sharedInstance().findOrCreate()
+    guard let uuid = TAKUUIDStorage.sharedInstance().findOrCreate() else { return }
     print("uuid = \(uuid)")
     print("lastErrorStatus = \(TAKUUIDStorage.sharedInstance().lastErrorStatus)")
   }
   
   @IBAction func renew() {
-    let uuid = TAKUUIDStorage.sharedInstance().renew()
+    guard let uuid = TAKUUIDStorage.sharedInstance().renew() else { return }
     print("uuid = \(uuid)")
     print("lastErrorStatus = \(TAKUUIDStorage.sharedInstance().lastErrorStatus)")
   }
diff --git a/Gemfile b/Gemfile
index f64c938..83cab23 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,3 +1,3 @@
 source "https://rubygems.org"
 
-gem 'cocoapods', '~> 1.1.0.rc.2'
+gem 'cocoapods', '~> 1.2', '>= 1.2.1'
diff --git a/Gemfile.lock b/Gemfile.lock
index 2e9ab07..99bfb50 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,69 +1,72 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    activesupport (4.2.7.1)
+    CFPropertyList (2.3.5)
+    activesupport (4.2.8)
       i18n (~> 0.7)
-      json (~> 1.7, >= 1.7.7)
       minitest (~> 5.1)
       thread_safe (~> 0.3, >= 0.3.4)
       tzinfo (~> 1.1)
-    claide (1.0.0)
-    cocoapods (1.1.0.rc.2)
+    claide (1.0.2)
+    cocoapods (1.2.1)
       activesupport (>= 4.0.2, < 5)
-      claide (>= 1.0.0, < 2.0)
-      cocoapods-core (= 1.1.0.rc.2)
+      claide (>= 1.0.1, < 2.0)
+      cocoapods-core (= 1.2.1)
       cocoapods-deintegrate (>= 1.0.1, < 2.0)
-      cocoapods-downloader (>= 1.1.1, < 2.0)
+      cocoapods-downloader (>= 1.1.3, < 2.0)
       cocoapods-plugins (>= 1.0.0, < 2.0)
       cocoapods-search (>= 1.0.0, < 2.0)
       cocoapods-stats (>= 1.0.0, < 2.0)
-      cocoapods-trunk (>= 1.0.0, < 2.0)
+      cocoapods-trunk (>= 1.2.0, < 2.0)
       cocoapods-try (>= 1.1.0, < 2.0)
-      colored (~> 1.2)
+      colored2 (~> 3.1)
       escape (~> 0.0.4)
-      fourflusher (~> 1.0.1)
+      fourflusher (~> 2.0.1)
       gh_inspector (~> 1.0)
-      molinillo (~> 0.5.1)
+      molinillo (~> 0.5.7)
       nap (~> 1.0)
-      xcodeproj (>= 1.3.1, < 2.0)
-    cocoapods-core (1.1.0.rc.2)
+      ruby-macho (~> 1.1)
+      xcodeproj (>= 1.4.4, < 2.0)
+    cocoapods-core (1.2.1)
       activesupport (>= 4.0.2, < 5)
       fuzzy_match (~> 2.0.4)
       nap (~> 1.0)
     cocoapods-deintegrate (1.0.1)
-    cocoapods-downloader (1.1.1)
+    cocoapods-downloader (1.1.3)
     cocoapods-plugins (1.0.0)
       nap
     cocoapods-search (1.0.0)
     cocoapods-stats (1.0.0)
-    cocoapods-trunk (1.0.0)
+    cocoapods-trunk (1.2.0)
       nap (>= 0.8, < 2.0)
       netrc (= 0.7.8)
     cocoapods-try (1.1.0)
-    colored (1.2)
+    colored2 (3.1.2)
     escape (0.0.4)
-    fourflusher (1.0.1)
+    fourflusher (2.0.1)
     fuzzy_match (2.0.4)
-    gh_inspector (1.0.2)
-    i18n (0.7.0)
-    json (1.8.3)
-    minitest (5.9.1)
-    molinillo (0.5.1)
+    gh_inspector (1.0.3)
+    i18n (0.8.4)
+    minitest (5.10.2)
+    molinillo (0.5.7)
+    nanaimo (0.2.3)
     nap (1.1.0)
     netrc (0.7.8)
-    thread_safe (0.3.5)
-    tzinfo (1.2.2)
+    ruby-macho (1.1.0)
+    thread_safe (0.3.6)
+    tzinfo (1.2.3)
       thread_safe (~> 0.1)
-    xcodeproj (1.3.1)
-      activesupport (>= 3)
-      claide (>= 1.0.0, < 2.0)
-      colored (~> 1.2)
+    xcodeproj (1.5.0)
+      CFPropertyList (~> 2.3.3)
+      claide (>= 1.0.2, < 2.0)
+      colored2 (~> 3.1)
+      nanaimo (~> 0.2.3)
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
-  cocoapods (~> 1.1.0.rc.2)
+  cocoapods (~> 1.2, >= 1.2.1)
 
 BUNDLED WITH
-   1.12.5
+   1.14.6