Madhu Kalva
Unity: iOS build errors compilation
Updated: Nov 13, 2021
Invalid SWIFT_VERSION: Could not parse version component from: '1 5'
Select UnityFramework Target and go to Build Settings.
Change Swift Language Version from "Swift 5" to "Swift 5" (no mistake here).
Try deploying it again.

GoogleAppMeasurement requires CocoaPods version `>= 1.10.2, which is not satisfied by your current version, 1.10.1
First double-check cocopods version with
pod --version
you will realize it has cocopods 1.10.1 version as is mentioned in the error. To fix this do the following
sudo gem uninstall cocoapods
sudo gem install cocoapods -v 1.10.2
Note: don't run sudo gem install cocoapods because it will get the latest cocopods which is probably not what you want.
Source: https://forum.unity.com/threads/cocoapods-installation-failure-when-building-for-ios.1167700/
Missing RegisterMonoModule.h
With Unity 2019.3 or above if you use Facebook SDK you will get this error Missing RegisterMonoModule.h while building in XCode.
To fix this you can use this - https://gist.github.com/ntratcliff/3942abd1eed9d704713a27616f09628b
Exception: Calling TargetGuidByName with name='Unity-iPhone' is deprecated.
In my case, I am using Unity 2019.4.17f1 and integrating MoPub for monetization. Then, I see this error when I try to build for iOS.
To fix this have to use GetUnityMainTargetGuid instead of TargetGuidByName.
So replace following
var target = project.TargetGuidByName("Unity-iPhone");
with
var target =
#if UNITY_2019_3_OR_NEWER
project.GetUnityMainTargetGuid();
#else
project.TargetGuidByName("Unity-iPhone");
#endif
Reference: https://github.com/mopub/mopub-unity-sdk/issues/111

'MoPub.h' file not found
When I integrated MoPub's Facebook Audience Network(FAN) mediation network, I saw this error. This is because FAN uses use_frameworks! and iOS won't build with use_frameworks! in Podfile.
Workaround:
Remove <iosPod name="MoPub-SDK-Plugin" minTargetSdk="10.0" path="Assets/MoPub/Plugins/iOS"/> from Assets/MoPub/Scripts/Editor/MoPubDependencies.xml
Delete Assets/MoPub/Plugins/iOS/MoPub-SDK-Plugin.podspec
Check iOS as platform for plugin for all files inside Assets/MoPub/Plugins/iOS

Reference: https://github.com/mopub/mopub-unity-sdk/issues/151