how to use MVVMLight SimpleIoc?

Question

I'm revamping my software which has messy Messenger.Default(...) bits.

Is there any cheat sheet to know MVVMLight SimpleIoc usage (not general IoC description)?

Answer 1

SimpleIoc crib sheet:

1) You register all your interfaces and objects in the ViewModelLocator

class ViewModelLocator 
{ 
    static ViewModelLocator() 
    {         
        ServiceLocator.SetLocatorProvider(() => SimpleIoc.Default);          
        if (ViewModelBase.IsInDesignModeStatic) 
        {              
            SimpleIoc.Default.Register<IDataService, Design.DesignDataService>();          
        }          
        else         
        {              
            SimpleIoc.Default.Register<IDataService, DataService>();          
        }          
        SimpleIoc.Default.Register<MainViewModel>();                  
        SimpleIoc.Default.Register<SecondViewModel>(); 
    }      


    public MainViewModel Main 
    {  
        get  
        {      
            return ServiceLocator.Current.GetInstance<MainViewModel>();  
        } 
    }
} 

2) Every object is a singleton by default. To resolve an object so that it's not a singleton you need to pass a unique value to the GetInstance call:

SimpleIoc.Default.GetInstance<MainViewModel>(Guid.NewGuid().ToString());

3) To register a class against an interface:

SimpleIoc.Default.Register<IDataService, Design.DesignDataService>();  

4) To register a concrete object against an interface:

SimpleIoc.Default.Register<IDataService>(myObject);     

5) To register a concrete type:

SimpleIoc.Default.Register<MainViewModel>();   

6) To resolve an object from an interface:

SimpleIoc.Default.GetInstance<IDataService>();

7) To resolve an object directly (does buildup and dependency resolution):

SimpleIoc.Default.GetInstance<MainViewModel>();

8) MVVM makes doing design-time data really easy:

if (ViewModelBase.IsInDesignModeStatic) 
{              
    SimpleIoc.Default.Register<IDataService, Design.DesignDataService>();          
}          
else         
{              
    SimpleIoc.Default.Register<IDataService, DataService>();          
}  

If you're in design-time mode it will automatically register your design-time services, making it really easy to have data in your viewmodels and views when working in the VS designer.

Hope this helps.