How to filter English letters in String? : <p>How to filter English letters in String using Swift like this:</p>

<p><code>
2017-08-23T13:00:00+08:00
</code></p>

<p>Delete the 'T' in time string:</p>

<p><code>
2017-08-23 13:00:00 +08:00
</code></p>
