Delegate wrapper examples, might not be the best.

DelegateTest.cpp

#include "DelegateTest.h"

void UDelegateTest::RegisterDelegate(FOnDelegate& Del)
{
	if (!OnDelegate.IsBound())
	{
		OnDelegate = Del;
		return;
	}
	UE_LOG(LogTemp, Warning, TEXT("OnComplete already Bound, ignoring as I can only have one binding."));
}

void UDelegateTest::RegisterMulti(FOnMulti::FDelegate& Del)
{
	// uncomment if you want to ensure uniqueness
	//if (!OnMulti.IsBoundToObject(Del.GetUObject()))
	{
		OnMulti.Add(Del);
	}
}

void UDelegateTest::UnregisterDelegate()
{
	if (OnDelegate.IsBound())
	{
		OnDelegate.Unbind();
	}
}

bool UDelegateTest::UnregisterMulti(FOnMulti::FDelegate& Del)
{
	if (OnMulti.IsBoundToObject(Del.GetUObject()))
	{
		return OnMulti.Remove(Del.GetHandle());
	}
	UE_LOG(LogTemp, Warning, TEXT("OnMulti doesn't have that binding."));
	return false;
}

void UDelegateTest::ExecuteDelegates()
{
	OnDelegate.ExecuteIfBound(this);
	OnMulti.Broadcast(this);
}

DelegateTest.h

#pragma once

#include "CoreMinimal.h"
#include "DelegateTest.generated.h"

class UDelegateTest;
DECLARE_DELEGATE_OneParam(FOnDelegate, UDelegateTest*);
DECLARE_MULTICAST_DELEGATE_OneParam(FOnMulti, UDelegateTest*);

UCLASS()
class TDTD_CPP_API UDelegateTest : public UObject
{
	GENERATED_BODY()
public:
	UDelegateTest() {  }
	int called = 0;
	
	// Define delegates and Register/Unregister
	FOnDelegate OnDelegate;
	FOnMulti OnMulti;
	
	void RegisterDelegate(FOnDelegate& Del);
	void RegisterMulti(FOnMulti::FDelegate& Del);
	void UnregisterDelegate();
	bool UnregisterMulti(FOnMulti::FDelegate& Del);
    
	void ExecuteDelegates();
};

DelegateTester.cpp

#include "DelegateTester.h"

void UDelegateTester::SetupTest()
{
	UDelegateTest* Test = NewObject<UDelegateTest>(this);
  
	// Generate a regular Delegate and bind
	FOnDelegate OnDelegate = FOnDelegate::CreateUObject(this, &UDelegateTester::Test);
	Test->RegisterDelegate(OnDelegate);

	// Generate a Multicast Delegate and bind
	FOnMulti::FDelegate OnDoneMulti = FOnMulti::FDelegate::CreateUObject(this, &UDelegateTester::Test);
	Test->RegisterMulti(OnDoneMulti);
	// if allowed, you can register one delegate multiple times
	Test->RegisterMulti(OnDoneMulti);
	// if the Delegate is defined the same as the Multicast Delegate, you can use it as well
	Test->RegisterMulti(OnDelegate);
  
	// will print 4 times
	Test->ExecuteDelegates();
  
	// unregister existing binding
	Test->UnregisterDelegate();

	// unregister works only if it's with the same FDelegate, and will only remove one instance
	Test->UnregisterMulti(OnDoneMulti);
  
	// doesn't work to remove existing multicast delegates, as the Handle ID is different
	FOnMulti::FDelegate OnDoneMulti2 = FOnMulti::FDelegate::CreateUObject(this, &UDelegateTester::Test);
	if(!Test->UnregisterMulti(OnDoneMulti2))
		UE_LOG(LogTemp, Warning, TEXT("OnDoneMulti2 wasn't unbound."));
  
	// will print 2 times
	Test->ExecuteDelegates();
  
	// cleanup
	Test->UnregisterMulti(OnDelegate);
	Test->UnregisterMulti(OnDoneMulti);
  
	// will not print
	Test->ExecuteDelegates();
}

void UDelegateTester::Test(UDelegateTest* Test)
{
	UE_LOG(LogTemp, Display, TEXT("Test called %d times."), Test->called++);
}

DelegateTester.h

#pragma once

#include "CoreMinimal.h"
#include "UObject/Object.h"
#include "DelegateTest.h"
#include "DelegateTester.generated.h"

UCLASS()
class TDTD_CPP_API UDelegateTester : public UObject
{
public:
	GENERATED_BODY()
	void SetupTest();
	void Test(UDelegateTest* Test);
};