implementing captcha in ipad

I am new to iPhone development. how is captcha in iphone implement开发者_JAVA技巧ed. Please tell me if anyone can shed some light on this.

Any help is appreciated.

Thanks in advance

You really need captcha on iPhone when your client app have ability of registering new users on you server. Someone may crack your app and stole the registration protocol.

But I found the solution. Just use APN :

• Client-app generates APN_id and sends it to server.
• Server pushes notification with random string to client thru APN.
• Client sends this string to server and server now may accept registrations from client.

Bit of a strange question if you ask me. Captcha is not implemented into iphone, it isn't implementent in a browser on a computer either. It's serverside parsed and handled.

*tip for free, use gestures instead of captcha for touch devices