Fix build error "Property with 'retain (or strong)' attribute must be of object type"

I ran into this issue trying to build a new project using SVHTTPRequest (obviously) :
    
    Property with 'retain (or strong)' attribute must be of object type

I'm not sure about this fix but it worked for me. 
I'm using XCode 4.6.3 on a brand new project targeting 6.1, if it helps...