Unity Container Lifetime Scope of Instance of Registered Type

In this blog, we will discuss about lifetime scope of instance of register type created by Unity Container and how to manage it

Container.RegisterInstance(typeof(ProjectEngine), new ProjectEngine ())

By default, the RegisterInstance method registers existing object instances with a container-controlled lifetime [ContainerControlledLifetimeManager] it means that unity registers an object as a singleton instance.

By default lifetime for RegisterType method is TransientLifetimeManager, which creates new object of request type for each call.

Container.RegisterType<IProjectEngine, ProjectEngine>(); 

OR

Container.RegisterType<IProjectEngine, ProjectEngine>(new TransientLifetimeManager()); 

Unity Container have other lifetime managers so you can able to manage lifetime of created object differently.

Lifetime Manager	Description
TransientLifetimeManager	Unity Creates a new instance of request type for each call, when you call Resolve method
ContainerControlledLifetimeManager	Unity creates a singleton object of request type on first call and it returns same object for subsequent Resolve call
HierarchicalLifetimeManager	Its same as ContainerControllerLifeTimeManager, only difference is that child and parent container creates its own singleton object and but both don’t share its singleton object
PerResolveLifetimeManager	It is same as TransientLifeTimeManager but it reuse same instanced object in the recursive object graph
PerThreadLifetimeManager	Unity Creates a singleton object per thread basis
ExternallyControlledLifetimeManager	It delegate to external source to manage the object and but for first resolve call, it creates object of requested type.

other dependency injection and unity container  related posts : 

What is Dependency Injection

Unity Container Register Singleton Class

Dependency Injection with Entity Framework DbContext

Dependency Injection using Unity container

C# Unit Testing - Dependency Injection , Moq