[React Native]FlatListのdataを変更しても画面が更新されない

[17:19:16] VirtualizedList: missing keys for items, make sure to specify a key property on each item or provide a custom keyExtractor., 
- node_modules\expo\build\logs\LogSerialization.js:145:14 in _captureConsoleStackTrace
- node_modules\expo\build\logs\LogSerialization.js:40:24 in Object.serializeLogDataAsync$
- ... 9 more stack frames from framework internals

          <FlatList 
            data={this.state.data}
            execData={this.state.update}
            keyExtractor={(item, index) => index.toString()}  // warningがでなくなった
            renderItem={({item}) => 
              <Swipeout 
              autoClose={true}
                sectionID={item.rowid}
                rowID={item.rowid}

Basic FlatList code throws Warning - React Native