Android-only API to listen to the hardware back button.
Methods
exitApp
exitApp: unit => unit
addEventListener
addEventListener: ([#hardwareBackPress], unit => nullable<bool>) => {remove: unit => unit}
Return Nullable.make(true) from the handler to prevent the default back
behavior.
React.useEffect0(() => {
let subscription = BackHandler.addEventListener(#hardwareBackPress, () => {
// handle back...
Nullable.make(true)
})
Some(() => subscription.remove())
})