Can I slow down my iPhones network connection while testing an app?

I'm trying to test an iPhone app that needs to be usable in low-bandwidth / poor signal areas. I know I can slow the network on my Mac and the simulator in Xcode, but not how to slow iOS and iPadOS devices.

Can I slow the network connection on the physical devices?

Solution 1:

Network Link Conditioner should do what you want. It's part of "Additional Tools for Xcode" and can be downloaded here:
https://developer.apple.com/download/all/?q=Additional%20Tools

Attach your iPhone to your Mac, launch Xcode and go to...

Window > Devices & Simulators

Select your iPhone in the sidebar (unlocked and displayed without errors)

On the iPhone you should now have the Developer settings:

Settings > Developer > Networking > Network Link Conditioner

See also: https://nshipster.com/network-link-conditioner/#enabling-network-link-conditioner-on-ios-devices