Вот пример:
Navigation.startTabBasedApp({
tabs: [
{
screen: "screen1",
icon: require("../sharedAssets/image.png"),
label: "label1",
},
{
screen: "screen2"
icon: require("../sharedAssets/image2.png"),
label: "label2",
}
],
tabsStyle: {
initialTabIndex: 1, // optional, the default selected bottom tab. Default: 0
}
})