The property iosDisplayInForeground isnt working since v33. Hopefully looking forward to sdk35. For now i do the same as fanofskynyrd and catch the notifications into an alert window. Alternativly you can try react-native-dropdownalert which is working too. But you have to know, you have to use the data attribute to receive and show the data.
example:
{ "title" : "mytitle",
"body" : "mybody",
"data" : {
"title" : "this title u can use",
"body" : "this body u can use in your alert"
}
}