format option should accept string or symbol.

[grossjo]

Crashes is a string is passed for format.

[NicosKaralis]

sorry, could you elaborate your problem? i can't understand what is happening to you

[btate]

I'm having the same thing. I'm saving my extra data as a json string in my database. So I need to pass that string in the :other section of APNS.

[NicosKaralis]

Can you elaborate more? Which method are you running that gives this error?

This should work, just remember :other should be a hash because the payload needs a key, if other is a string it cannot infer a key to use (should check that on future version)

APNS.send_notification(device_token, :alert => 'Hello iPhone!', :badge => 1, :sound => 'default', 
                                :other => {:string => 'object transformed to json string'})