UFunction in Unreal Engine 5 C++

Exposes a function to Unreal's reflection system

Syntax

UFUNCTION(BlueprintCallable, Category="Custom Category")
bool MyFunction(int32 MyArg);

BlueprintImplementableEvent Specifier

Converts a function into an event inside the Blueprint event graph given the following conditions:

1. Function must have return type void
2. Function must only be declared NOT defined in c++

UFUNCTION(BlueprintImplementableEvent)
void MyFunction(int32 MyArg);  // do not define this inside .cpp file

BlueprintNativeEvent Specifier

Allows a function to be overriden inside blueprint

// .h file
UFUNCTION(BlueprintCallable, BlueprintNativeEvent)
bool MyFunction(int32 MyArg);  // Make sure to add *_Implementation when defining the function


// .cpp file
bool UExample::MyFunction_Implementation(int32 MyArg){  // *_Implementation
    ...
    return true;
}

All Specifiers

BlueprintCallable  // Allows function to be called inside blueprints

BlueprintImplementableEvent  // Allows function to become event, Note: function must return void & must only be declared NOT defined in c++
BlueprintNativeEvent  // Allows a function to be overriden inside blueprint, Note: function definition inside .cpp must have *_Implementation suffix

Category = "My Category | My Sub Category"  // Allows property to be placed in the given category

Meta Specifiers

// Use Syntax UFUNCTION(meta=(...))

DisplayName = "My Function"  // Allows function name to be different inside editor

AllowPrivateAccess = "true"  // Allows function to be placed inside `private` Access Specifier of the class

BlueprintProtected  // Only let's function be invoked in the defining blueprint i.e. Same behaviour as `protected` Access Specifier of classes