Based on the community answers, there does not appear to be a reliable iOS app that gives Canon 6D/70D built-in Wi-Fi timelapse control comparable to DSLR Controller on Android.

What was suggested:

• Cascable: a possible alternative to Canon Camera Connect/EOS Remote for live view shooting and bulk image transfer.
• Triggertrap: useful for timelapse and specialty trigger modes, but it works via a cable/trigger setup rather than the camera’s internal Wi-Fi.
• Intervalometer: the most straightforward option for timelapse if Wi-Fi control is the requirement that’s causing problems.

So if your priority is specifically timelapse over the 6D/70D’s internal Wi-Fi from iOS, the answers indicate that a good solution likely doesn’t exist. If you can give up the Wi-Fi requirement, a wired intervalometer or Triggertrap-style setup is the practical workaround. If you mainly want remote shooting and image transfer on iOS, Cascable is the app most worth trying.