How to do it...

1. In Settings | Project Settings | Input, define a new Action Mapping for your hot key event, for example, HotKey_UIButton_Spell:

2. Wire up the event to your UI's function call either in Blueprints or in C++ code. In our case, I will add it to the AWarrior class we created previously by adding it to the SetupPlayerInputComponent function:

#include "Chapter_06GameModeBase.h"

// ...

// Called to bind functionality to input
void AWarrior::SetupPlayerInputComponent(UInputComponent* PlayerInputComponent)
{
    Super::SetupPlayerInputComponent(PlayerInputComponent);

    check(PlayerInputComponent);
    PlayerInputComponent->BindAxis("Forward", this, 
    &AWarrior::Forward);
    PlayerInputComponent->BindAxis("Back", this, &AWarrior::Back);
    PlayerInputComponent->BindAxis("Right", this, &AWarrior::Right);
    PlayerInputComponent->BindAxis("Left", this, &AWarrior::Left);

    PlayerInputComponent->BindAction("Jump", IE_Pressed, this, 
    &AWarrior::Jump);

    // Example of adding bindings via code instead of the 
    //  editor
    FInputAxisKeyMapping backKey("Back", EKeys::S, 1.f);
    FInputActionKeyMapping jump("Jump", EKeys::SpaceBar, 0, 0, 
    0, 0);

    GetWorld()->GetFirstPlayerController()->PlayerInput-
    >AddAxisMapping(backKey);
    GetWorld()->GetFirstPlayerController()->PlayerInput-
    >AddActionMapping(jump);

    // Calling function for HotKey
    auto GameMode = Cast<AChapter_06GameModeBase>(GetWorld()-
    >GetAuthGameMode());
    auto Func = &AChapter_06GameModeBase::ButtonClicked;

    if(GameMode && Func)
    {
        PlayerInputComponent->BindAction("HotKey_UIButton_Spell", 
                                         IE_Pressed, GameMode,  
                                         Func);
    }
    
}

3. Compile your script and then open the World Settings by going to Settings | World Settings. Under Selected GameMode, set the Default Pawn Class to BP_Warrior. You should now notice that you can either press your key or press the button to execute the ButtonClicked function we created in the previous recipe!