Handwritten signature on mail in iPad

I want to include handwritten signature of user on the email I am composing from code. I was following this tutorial for capturing hand开发者_如何学JAVAwritten signature on device. But the only problem I am facing is how to implement this code on mail. How can I handle touch events of mail.

What I decided for a moment was to capture a portion of mail screen on iPad on whose touching I can create a view where user can enter his/her signature which can further be saved. The only problem is implementing this.

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I dont think you can capture touches on mail composer. The best approach would be to ask user to sign and then present the mail composer with sign as attachment