How to change iOS simulator language to swedish

Choose Svenska. You can select the language through the settings just like you would on a real device. Languages are displayed in the target language, not the current language, as displayed in your screenshot.

Tap the row you want, then tap done (click in the case of the simulator). On device, make sure you can navigate back.

It is also possible to set the language and the region via the scheme settings as seen here:

If you are trying to test an application's localisations then there are easier ways than by changing the language on the device.

You can run the apps with a flag to indicate the country:

i.e for Swedish you can use the flag -AppleLanguages (sv)

Of course, on the simulator or the device, you can't run an app with a flag normally, except for when you are building and running it through Xcode, where you can set the launch arguments for each scheme.

I wrote about this in greater detail, with screenshots, and an example project: https://abizern.org/2012/03/18/simple-localisation-testing.html

This works for the simulator and the device, and you don't have to change any of the device settings.