iOS build not displaying updated content on subsequent re-builds

I am using Ionic 3 and building an existing app for iOS. I can build the app for iOS and run the app on a real device, but when I make a change to my ionic src code, and do a rebuild and run on the device, the changes don’t show.

I have tried generating a new Ionic 3 app and changes do appear after each rebuild. So I assume that there must be something wrong or misconfigured within my existing app.

I am using XCode Version 10.1

Help much appreciated

ionic info:

cli packages: (/usr/local/lib/node_modules)

    @ionic/cli-utils  : 1.19.2
    ionic (Ionic CLI) : 3.20.0

global packages:

    cordova (Cordova CLI) : not installed

local packages:

    @ionic/app-scripts : 3.2.0
    Cordova Platforms  : none
    Ionic Framework    : ionic-angular 3.9.2

System:

    ios-deploy : 1.9.4
    Node       : v10.15.0
    npm        : 6.4.1
    OS         : macOS
    Xcode      : Xcode 10.1 Build version 10B61

Environment Variables:

    ANDROID_HOME : not set

Misc:

    backend : pro

Found the solution:

Call

sudo ionic cordova prepare ios

Prior to calling

sudo ionic cordova build ios

Changes to the src are now reflected in the generated iOS build