System::SharedPtr<Project> project1 = System::MakeObject<Project>(dataDir + u"Blank2010.mpp");
        
System::SharedPtr<ExtendedAttributeDefinition> myTextAttributeDefinition = project1->get_ExtendedAttributes()->GetById((int32_t)Aspose::Tasks::ExtendedAttributeTask::Text1);
        
// If the Custom field doesn't exist in Project, create it
if (myTextAttributeDefinition == nullptr)
{
    myTextAttributeDefinition = ExtendedAttributeDefinition::CreateTaskDefinition(Aspose::Tasks::ExtendedAttributeTask::Text1, u"My text field");
    project1->get_ExtendedAttributes()->Add(myTextAttributeDefinition);
}
        
// Generate Extended Attribute from definition
System::SharedPtr<ExtendedAttribute> text1TaskAttribute = myTextAttributeDefinition->CreateExtendedAttribute();
        
text1TaskAttribute->set_TextValue(u"Text attribute value");
        
// Add extended attribute to task
System::SharedPtr<Task> tsk = project1->get_RootTask()->get_Children()->Add(u"Task 1");
tsk->get_ExtendedAttributes()->Add(text1TaskAttribute);
        
project1->Save(dataDir + u"CreateExtendedAttributes_out.mpp", Aspose::Tasks::Saving::SaveFileFormat::MPP);