When working with Swift/iOS development the only choice of IDE is Xcode, which can only be install on a Mac.
In the case you do not have access to an Mac computer, you can also achieve the same result by renting remote access to a Mac. This can be done by the help of services like MacStadium.
The cost of one of these services are relatively high on a monthly basis. I would therefore suggest that you purchase a Mac computer if you are planning to continuously create new iOS app. However, if it is only for a limited amount of time, these types of services will be a better financial choice for you.
Beside Xcode enabling development and publication of iOS apps, it also have the capabilities to create testing emulators.
Xcode can be found and installed from the Mac app store.