title: How get all the keys of secureStorage with ionic 2?
body: <p>I'm trying to get all the keys stored in my secureStorage.</p>
  
  <p><a href="https://github.com/Crypho/cordova-plugin-secure-storage" rel="nofollow noreferrer">https://github.com/Crypho/cordova-plugin-secure-storage</a></p>
  
  <p>Then I have write a service with functions like: </p>
  
  <pre><code>getValue(item): any {
      return &lt;Promise&lt;any&gt;&gt; this.secureStorage.get(item);
  }
  </code></pre>
  
  <p>That works fine with Android, but with iOs it give an error:</p>
  
  <pre><code>EXCEPTION: Uncaught (in promise): Error: Failure in SecureStorage.get() - The specified item could not be found in the keychain
  </code></pre>
  
  <p>I throught that the error came, when I do a get, for example:</p>
  
  <pre><code>this.myService.getValue('item1').then(
                          (data) =&gt; {
  console.log(data);
  });
  </code></pre>
  
  <p>If I understand, in the keychain, there are no value item1, but how can I test if a value exists before doing a get?</p>
  
  <p>In the documentation, it's a keys function, which has to give me all the keys. But this function don't work for me:</p>
  
  <pre><code>getAllKeys(item): any {
       &lt;Promise&lt;any&gt;&gt; this.secureStorage.keys();
  }
  </code></pre>
  
  <p>That give for me a:</p>
  
  <pre><code>this.myService.keys is not a function
  </code></pre>
  
  <p>I'm using ionic 2.</p>
  
  <p>What I'm doing wrong?</p>
  
  <p>Thanks</p>