Content in an iframe will get indexed, but on the URL where that content sits. It’s not seen as part of the page that contains the iframe. This is one of the reasons frames in general may not be a good idea.
The engines all interpret content in an embedded IFrame as belonging to a separate document from the page displaying the IFrame content. Thus links and content inside IFrames refer to the page they come from, rather than the page they are placed on. For SEO, one of the biggest implications of this is that links inside an IFrame are interpreted as internal links (coming from the site the IFrame content is on) rather than external links (coming from the site embedding the IFrame)
Iframes are treated as content from some other website. So if your iframe content is getting indexed, you probably will not get credit for this. Rather, the website of iframe content will get the credit. iframes, certainly, not a good idea for me.