Here is how I spawn a blueprint via C++. Note that the blueprint I spawn has a base class that was created in C++ also.
TSubclassOf<YourClass> BlueprintVar; // YourClass is the base class that your blueprint uses
ClassThatWillSpawnTheBlueprint::ClassThatWillSpawnTheBlueprint(const class FPostConstructInitializeProperties& PCIP) : Super(PCIP) ｛ static ConstructorHelpers::FObjectFinder<UBlueprint> PutNameHere(TEXT("Blueprint'/Path/To/Your/Blueprint/BP.BP'")); if (PutNameHere.Object) ｛ BlueprintVar = (UClass*)PutNameHere.Object->GeneratedClass; ｝ ｝
PutNameHere is just an arbitrary name you give to the constructor helper. The path to your blueprint is found by finding your blueprint in the content browser, right clicking it, and choosing Copy Reference. Then, just paste that in between the quotes.
Now, you're ready to spawn the blueprint. You can do it in BeginPlay() or wherever, just not in the constructor.（这段代码必须放在非构造函数中，比如BeginPlay()中）
UWorld* const World = GetWorld(); // get a reference to the world if (World) ｛ // if world exists YourClass* YC = World->SpawnActor<YourClass>(BlueprintVar, SpawnLocation, SpawnRotation); ｝
If you don't know your SpawnLocation or SpawnRotation you can just throw in FVector(0,0,0) and FRotator(0,0,0) instead.
So, since your blueprint base class was also created in C++ this makes it easy to interact with your blueprint from code. It's as simple as YC->SomeVariable = SomeValue. Hope that helps.