Ios – How to create a GCD queue which is always serial, even on multi-core CPUs

A simple example: you have a block that takes a minute to execute. You add it to a queue from the main thread. Let's look at the four cases.

• async - concurrent: the code runs on a background thread. Control returns immediately to the main thread (and UI). The block can't assume that it's the only block running on that queue
• async - serial: the code runs on a background thread. Control returns immediately to the main thread. The block can assume that it's the only block running on that queue
• sync - concurrent: the code runs on a background thread but the main thread waits for it to finish, blocking any updates to the UI. The block can't assume that it's the only block running on that queue (I could have added another block using async a few seconds previously)
• sync - serial: the code runs on a background thread but the main thread waits for it to finish, blocking any updates to the UI. The block can assume that it's the only block running on that queue

Obviously you wouldn't use either of the last two for long running processes. You normally see it when you're trying to update the UI (always on the main thread) from something that may be running on another thread.

had the same issue once, in my case i didnt have my server well configured, i fix it by configuring apache2 with the rewrite module, in linux it should by sometinhg like this sudo a2enmod rewrite, pluss in your site configuration site in etc/apache/sites-available/example.dev you should have something like this

NameVirtualHost 127.0.0.1

<VirtualHost 127.0.0.1>
  ServerName example.dev
  DocumentRoot "/var/www/intranetcms/web"
  DirectoryIndex app.php
  <Directory "/var/www/intranetcms/web">
    AllowOverride All
    Allow from All
  </Directory>
</VirtualHost>

if you dont know how to configure a local domain here is an example http://tutorial.symblog.co.uk/docs/configuration-and-templating.html but if you dont feel like configuring a local domain you can check the default site configuration file in /etc/apache2/sites-enabled/default and change AllowOverride None for AllowOverride All