MFMailComposer custom buttons

I know it is possible to change the navbar image on a MFMailComposer. Is it possible to customize the Cancel and Send buttons too? I want to use custom images for the backgrounds of the buttons so just changing the tint won't do.

Thanks for your answers.

开发者_运维知识库EDIT

This is what I'm trying to achieve:

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Try accessing them through mailComposeViewController.navigationBar.items, which is an array of the bar items.