How To: Make Devise work with other formats like mobile, iphone and ipad (Rails specific)

1.Make your app render Apple iOS templates for iOS devices like iPhone, iPad, iPod Touch, etc. In the Rails app/controllers/application_controller.rb add this code:

  before_filter :adjust_format_for_iphone
  private
    def adjust_format_for_iphone    
          request.format = :ios if ios_user_agent?
    end
    
    def ios_user_agent?
        request.env["HTTP_USER_AGENT"]
        request.env["HTTP_USER_AGENT"][/(Mobile\/.+Safari)/]
    end
```

2.Set Devise to display views for iOS
In the `config/initializers/devise.rb`, look for the 'config.navigational_formats' and add every other formats you have
`config.navigational_formats = [:"*/*", "*/*", :html, :ios]`

3.Create each view you need for Devise (login form, signup form, ...)
Name your view like 'new.**ios**.erb'
eg: 'app/views/devise/sessions/new.ios.erb' for login form

4.Create an initializer in the folder config/initializers
Add this code into your initializer

```ruby
ActionController::Responder.class_eval do
  alias :to_ios :to_html
end
```
This code has to correspond to your format (ie: :to_ios, :to_ipad, :to_mobile)

5.Add your format to config/initilaizers/mime_types.rb

```Mime::Type.register_alias "text/html", :ios
```