title: How to get notified when a user default changed?
body: <p>I have a user default called <code>showSqliteSequenceTable</code> and this can be changed with a checkbox. I use this as follows, in a method called <code>-[SKDatabase reloadTables]</code>:</p>
  
  <pre><code>const char *tablesQuery = [[NSUserDefaults standardUserDefaults] boolForKey:@"showSqliteSequenceTable"] ? "SELECT name FROM sqlite_master WHERE type='table'" : "SELECT name FROM sqlite_master WHERE type='table' AND NOT name='sqlite_sequence'";
  </code></pre>
  
  <p>What way can I get the <code>-[SKDatabase reloadTables]</code> message sent to every <code>SKDatabase</code> object in memory, or how can I make <code>SKDatabase</code> observe a user default? Thanks.</p>