Author: admin

preflight response issue with ionic3 app on ios build only [ resolved ]


I was running with the same problem, My ionic 3 app with backend was working just fine, it was not working with IOS ( Iphone x – IoS 11 simulator ). I got some errors like the following.

[Error] failed to load resource: Preflight response is not successful.

[Error] Failed to load resource: Origin http://localhost:8080 is not allowed by Access-Control-Allow-Origin.

I’m not seeing this issue from the Android version of the application. Is there a setting or something that can be enabled within the Ionic app to fix the CORS issue?


Workaround only – Not a perfect solution

I changed the `web view` option of my ionic app.
WKWebView ===> UIWebView

First, open config.xml and add the following properties

<feature name="CDVWKWebViewEngine">
<param name="ios-package" value="CDVWKWebViewEngine" />
<preference name="CordovaWebViewEngine" value="CDVWKWebViewEngine" />

then run the following commands – I hope you are familiar with this commands

ionic cordova plugin remove cordova cordova-plugin-ionic-webview --save
rm -rf platforms/
rm -rf plugins/
ionic cordova build ios



In iOS, there have been two webviews for a few years now, UIWebView and WKWebView. Historically, Ionic apps have used UIWebView, but no longer. Ionic now uses WKWebview by default when building for iOS.

We strongly believe WKWebview is the best option for any app, as it features many improvements over the older, legacy webview (UIWebView). These features include:

  • JIT conversion of JS code down to machine code, which runs much faster
  • Improved rendering performance
  • Less memory consumption
  • Better adherence to web standards
  • Reliable scroll events (important for virtual-list)

We wanted to make sure that people could easily switch to WKWebView without many issues, but there are still some things that you’ll need to consider.

Reference : Ionic wkwebview


Google Cloud Firestore is database service from google and is has very similar features like firebase realtime data base. It is a NoSQL database like MongoDB and it will sync the data with all connected applications automatically in real time.

It has some cool properties like multi regional data replication, multi document transaction and much more..

Key features of Cloud Firestore include:

  • Documents and collections with powerful querying
  • iOS, Android, and Web SDKs with offline data access
  • Real-time data synchronization
  • Automatic, multi-region data replication with strong consistency
  • Node, Python, Go, and Java server SDKs

Right now it is available for the developers in BETA mode, however google may release the stable version with in few months.

What is the difference between Firebase Realtime Database and FireStore ?

Firebase realtime db does not offer the actual NoSQL database however can be store data like a tree structure.

This is a best tutorial for some one who would like to get started with Google Cloud Firestore SDK.

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