nRF Loader is an app that uploads firmware to a device running Nordic Semiconductor's old DFU service. Number of binary files are embedded in this app which can be written to any device advertising the appropriate service.
A .bin file can be opened directly with nRF Loader from other iOS apps, so if you have an application as .bin file in an email or in Dropbox, you can open it with nRF Loader to upload the application to a target.
Note. This app is not compatible with new Nordic Semiconductor's DFU firmware. New DFU feature is available inside [nRF Toolbox] https://github.com/NordicSemiconductor/IOS-nRF-Toolbox