Based on the provided source material, there is no information confirming that Isiaka is a city in Nigeria. Instead, the name Isiaka is identified as both a given name and a surname.
Notable individuals with this name include Nigerian politician Isiaka Adeleke (1955–2017), air marshal Isiaka Oladayo Amao, and footballers Isiaka Olawale and Raheem Owolabi Isiaka.