Book Image

React Native By Example

By : Richard Kho
Book Image

React Native By Example

By: Richard Kho

Overview of this book

React Native's ability to build performant mobile applications with JavaScript has resulted in its popularity amongst developers. Developers now have the luxury to create incredible mobile experiences that look and feel native to their platforms with the comfort of a well-known language and the popular React.js library. This book will show you how to build your own native mobile applications for the iOS and Android platforms while leveraging the finesse and simplicity of JavaScript and React. Throughout the book you will build three projects, each of increasing complexity. You will also link up with the third-party Facebook SDK, convert an app to support the Redux architecture, and learn the process involved in making your apps available for sale on the iOS App Store and Google Play. At the end of this book, you will have learned and implemented a wide breadth of core APIs and components found in the React Native framework that are necessary in creating great mobile experiences.
Table of Contents (17 chapters)
Title Page
About the Author
About the Reviewer
Customer Feedback

Using onLayout

In our preceding example, we don't need to specify the height of the DatePickerIOS component when expanded. However, there may be scenarios in which you may need to manually get the dimensions of a component.

To calculate a component's height, we can utilize its onLayout property to fire a callback and then use that callback to save properties passed to the callback. The onLayout property is an event that is invoked on mount and layout changes, giving the event object a nativeEvent object that nests the component's layout properties. Using DatePickerIOS as an example, you can pass a callback to its onLayout prop like this:

  date={ } 
  onDateChange={ (date) => this._onDateChange(date) } 
  onLayout={ (event) => this._getComponentDimensions(event) } 
  style={ styles.datePicker }  


The event from onLayout gives access to the following property:

event: { 
  nativeEvent: { 
    layout: { 
      x: //some number 
      y: //some number...