In software development, IoC and dependency injection solve many problems. In the world of mobile development, particularly multi-platform mobile development, they provide a great pattern to handle platform- and device-specific code. One of the most important aspects of multi-platform mobile development is the idea of sharing code. Not only does development become easier and quicker when code can be shared across apps and platforms, but so does maintenance, management, feature parity, and so on. However, there are always parts of an app's code base that simply cannot be shared due to its strict tie-in with the platform's APIs. In most cases, an app's user interface represents a large portion of this non-sharable code. It is because of this that the MVVM pattern makes so much sense in multi-platform mobile development—it forces the separation of user interface code (Views) into individual, platform-specific, libraries, making it easy to then compartmentalize the rest of the code (ViewModels and Models) into a single, shareable library.

However, what if the code in the shared ViewModels needs to access the device's physical geolocation, or leverage the device's camera to take a photo? Since the ViewModels exist in a single platform-agnostic library, they can't call the platform-specific APIs. This is where dependency injection saves the day.