An error occurred when I was running "ionic cordova platform add ios"

This problem had been resolved by using commands

cordova platform rm ios
cordova platform add ios --nofetch

Your iOS platform seems to corrupted. Please remove and re-add the platform to resolve the issue using following commands:

cordova platform rm ios

cordova platform add ios

EDIT

If it happens when you try ionic cordova run/build android it will work with the same steps

cordova platform rm android

cordova platform add android

Then run ionic cordova run/build android and it will work.

If you are on linux or mac run the command with sudo. Problem solved.

Command-Example: sudo ionic cordova platform add android

OUTPUT:

$ sudo ionic cordova platform add android
> cordova platform add android --save

You have been opted out of telemetry. To change this, run: cordova telemetry on.
Using cordova-fetch for cordova-android@~7.1.1
Adding android project...
Creating Cordova project for the Android platform:
    Path: platforms/android
    Package: io.ionic.starter
    Name: MyApp
    Activity: MainActivity
    Android target: android-27
Android project created with [email protected]
Android Studio project detected
Android Studio project detected
Discovered plugin "cordova-plugin-whitelist" in config.xml. Adding it to the project
Installing "cordova-plugin-whitelist" for android

               This plugin is only applicable for versions of cordova-android greater than 4.0. If you have a previous platform version, you do *not* need this plugin since the whitelist will be built in.

Adding cordova-plugin-whitelist to package.json
Saved plugin info for "cordova-plugin-whitelist" to config.xml
Discovered plugin "cordova-plugin-statusbar" in config.xml. Adding it to the project
Installing "cordova-plugin-statusbar" for android
Adding cordova-plugin-statusbar to package.json
Saved plugin info for "cordova-plugin-statusbar" to config.xml
Discovered plugin "cordova-plugin-device" in config.xml. Adding it to the project
Installing "cordova-plugin-device" for android
Adding cordova-plugin-device to package.json
Saved plugin info for "cordova-plugin-device" to config.xml
Discovered plugin "cordova-plugin-splashscreen" in config.xml. Adding it to the project
Installing "cordova-plugin-splashscreen" for android
Adding cordova-plugin-splashscreen to package.json
Saved plugin info for "cordova-plugin-splashscreen" to config.xml
Discovered plugin "cordova-plugin-ionic-webview" in config.xml. Adding it to the project
Installing "cordova-plugin-ionic-webview" for android
Subproject Path: CordovaLib
Subproject Path: app
Adding cordova-plugin-ionic-webview to package.json
Saved plugin info for "cordova-plugin-ionic-webview" to config.xml
Discovered plugin "cordova-plugin-ionic-keyboard" in config.xml. Adding it to the project
Installing "cordova-plugin-ionic-keyboard" for android
Adding cordova-plugin-ionic-keyboard to package.json
Saved plugin info for "cordova-plugin-ionic-keyboard" to config.xml
--save flag or autosave detected
Saving android@~7.1.4 into config.xml file ...
> ionic cordova resources android --force
✔ Collecting resource configuration and source images - done!
✔ Filtering out image resources that do not need regeneration - done!
✔ Uploading source images to prepare for transformations: 2 / 2 complete - done!
✔ Generating platform resources: 18 / 18 complete - done!
✔ Modifying config.xml to add new image resources - done!

System Description:

Ubuntu 18.04 LTS

Ionic 4.5.0

Cordova 8.1.2

Node v8.14.0