"textAlignVertical" is not a valid style property

The textAlignVertical style is an Android-only property. If you are developing on iOS, try using the flexbox alignment property alignItems: center instead.

It also appears that the textAlignVertical property was moved from TextInput properties to the Text element styles only three days ago, and is going to be released in React Native 0.19.

I am not sure how the React Native documentation is generated, but based on my reading of this commit diff, the documentation appears to be ahead of the latest released version.

Sometimes you might find that alignItems won't work well -- I saw that an icon that I was using disappeared entirely. I instead just added an alignSelf: 'center' to the styling on the text itself (rather than the parent like you need to do with alignItems) and it seemed to fix it.

For textAlignVertical to work properly, add lineHeight prop instead of height for ios

height: phoneWidth * 0.09, // for android
lineHeight: phoneWidth * 0.09, // for ios