You use whoever to refer to someone when their identity is not yet known. 无论谁 (表示不确切知道是谁)
pronoun [指示代词] 无论谁；任何人
Whoever did this will sooner or later be caught and will be punished. 无论是谁干的，迟早都会被抓住并被惩罚。
noun [抽象名词] 爱谁谁
You can have whoever you like to visit you. 你可以让任何你想见的人拜访你。
