3-React Native for beginners - By Dhanraj Acharya

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v0.3.0 v0.4.0 Goals: Using the camera/BarCodeScanner modules from expo When we build a native application, we will most likely use native features. Before using the native features, we need to ask for the permissions for using them. We can do this by using Permission component from expo. We will ask for Camera permission. Another module we will use is BarCodeScanner to scan the barcode. It is just a wrapper over Camera module(You can also use Camera module directly to scan the barcode).
Open ScannerScreen.js and paste the below code. Look at the code and notice that we are checking the permissions in componentDidMount() method. Once the permission is given, we render the BarCodeScanner in the full screen. We overlay one History button to check the previous scanned QRs. Even when the QR code is scanned, it won’t stop the camera and will still try to scan the QRs. So when another screen will be in focus, still the camera will be active and it will keep scanning the QRs. To overcome this, we have wrapped our component in withNavigationFocus from reactnavigation. It gives us a method isFocused in the props to check whether the ScannerScreen is shown(Focused) on the actual device. We use this prop to conditionally render the BarCodeScanner component. Screens/ScannerScreen.js Screens/ScannerScreen.js Screens/ResultScreen.js In ResultScreen component, We just fetch the qr from the navigation parameters and show it in the Text component. Result Screens/ResultScreen.js
Page 1 and 2: While creating the App, I learned a
Page 3 and 4: Result v0.1.0 You can check out the
Page 5 and 6: Just as one can use URL/routes to s
Page 7 and 8: v0.2.0 If you’re curious about th
Page 9 and 10: SQLite When we want to save large a
Page 11: Finally, we have to call the InitDa
Page 17 and 18: Create a new file inside components
Page 21 and 22: v1.0.0 Source code The application

3-React Native for beginners - By Dhanraj Acharya

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