React native setState() not re-render as expected - react-native

Question

I made a carousel with react-native-snap-carousel and below are the code for carousel. In carousel there're picker and textInput and etc.
For render function:
<Carousel
ref={(c) => { this._carousel = c; }}
data={this.state.question}
renderItem={this._renderItem}
sliderWidth={standard * 1.1}
itemWidth={standard * 0.9}
inactiveSlideScale={0.9}
inactiveSlideOpacity={0.7}
firstItem={0}
activeSlideAlignment={'center'}
containerCustomStyle={styles.slider}
contentContainerCustomStyle={styles.sliderContentContainer}
/>
For detail rendering:
_renderItem ({item, index}) {
var content;
switch (item.id) {
case 1:
content = <View style={styles.carousel_cell}>
<Text style={styles.carouselItemTitle}>{item.displayLabel}</Text>
<TextInput style={styles.editor} onChangeText={(text) => this.setState({comment: text})} value={this.state.comment} />
</View>;
break;
case 2:
content = <View style={styles.carousel_cell}>
<Text style={styles.carouselItemTitle}>{item.displayLabel}</Text>
<Picker mode="dropdown"
style={styles.picker}
selectedValue={this.state.priority}
onValueChange={(itemValue) => this.onPriorityChange(itemValue)}>
{this.state.list}
</Picker>
</View>;
break;
default:
content = <View style={styles.carousel_cell}>
<Text style={styles.carouselItemTitle}>{item.displayLabel}</Text>
<Text>Unknown</Text>
</View>;
break;
}
return content;
}
For event triggering:
onPriorityChange(value) {
this.setState({priority: value});
}
The problem here is that after I select any item in Picker the state did get updated but on the interface it's not. The render function of Picker will be invoked once I trigger the onChangeText event. At that time the display in Picker will be update as well.
However, according to the life cycle, shouldn't the carousel(including its cells) be updated/re-rendered when I setState?
The Stopwatch(from react-native-stopwatch-timer) in carousel will have the same problem.

Answer 1

I don't know this package but the Carousel component seems to inherit from FlatList component.
The documentation says:
By passing extraData={this.state} to FlatList we make sure FlatList itself will re-render when the state.selected changes. Without setting this prop, FlatList would not know it needs to re-render any items because it is also a PureComponent and the prop comparison will not show any changes.
So, try to add extraData={this.state} to your Carousel component.