From spotlight search, try to write “Simulator”, which will most 
likely start an iPad. Go to “File->Open Simulator” and pick an iPhone.
Once that has started, close the iPad and run ns devices list

Copy what you find under "Device Identifier"
(for example E3270BFF-79A5-44A9-8119-5A398A3EA7CB)
and then run
ns run ios --no-hmr --device E3270BFF-79A5-44A9-8119-5A398A3EA7CB