MapMarker does not update description onPress immediately - reactjs

Question

I am trying to learn how to use React Native maps and I am trying to add in custom Map Markers. For some reason, when I try to use the following code, the image updates properly but the description does not update properly until the second click. The first click will show "not selected" but clicking on the same marker will show the actual text I want. How can I fix this?
Since the image is updating to the newImage, I know
this.state.selectedMarkerIndex === i
but the same equality does not apply to description for some reason?
state = {busText:[]}
fetchData=(i, index)=>{
fetch('LINK TO GET BUSES'+ i.toString() + '/buses', {method:'GET'})
.then((response) => response.json())
.then((responseJson) => {
this.setState({
selectedMarkerIndex: index,
busText: responseJson
},
()=>{
console.log("selected index: " + this.state.selectedMarkerIndex)
}
)
console.log(JSON.stringify(this.state.busText));
console.log("_______________________________________________________");
})
}
renderMarkers = ()=>{
return busStops.stops.map((stop, i) => {
return <Marker marker
key={ `${i}` }
coordinate={{latitude: stop.location.latitude, longitude: stop.location.longitude}}
title = {stop.stopName}
image = {this.state.selectedMarkerIndex === i ? newImage : busStopImage}
description={this.state.selectedMarkerIndex === i ? JSON.stringify(this.state.busText) : "not selected"}
onPress={() => {
this.fetchData(stop.stopID, i)
console.log(this.state.selectedMarkerIndex + "i :" + i)
}
}
/>
})
}
I expect the description of the MapMarker to be updated when I click on it with what is fetched but that is not occurring.

Answer 1

A couple of things: To guarantee execution after setState you'll need to put your
this.setState({busText: responseJson})
in the fetchData() callback. Even better, set busText state earlier, where you're setting selectedMarkerIndex state.
Also for what it's worth, if you're having response time issues, try dropping some of your console.log() calls. Native (especially iOS) gets bogged down by them.