Copying from SublimeText3 to Keynote:

ST3ToKeynote.markdown

• Assuming you're using the PackageControl.io module
• Install package named 'Highlight'. You don't need to create a repo or anything else.
• URL for the package (shouldn't need it) is https://packagecontrol.io/packages/Highlight
• Go to Preferences > Package Settings > SublimeHighlight and set the prefs otherwise pasted text looks awful. I use:

{
    "theme": "monokai",
    "linenos": "inline",
    "noclasses": true,
    "fontface": "Menlo"
}

• From the Command palette, chose SublimeHighlight: Copy to clipboard as RTF
• Paste into Keynote text box

There's something for textmate as well, called copy-with-style-tmbundle

Haven't tested out any XCode plugins yet, with the new XCode 7, that is.