Telerik Platform does not respect hooks in custom plugins as explained in this documentation article
. This said, the error is probably produced by the referenced library not being found.
When adding a custom plugin in AppBuilder ensure it meets the requirements for using plugins as explained here
Depending on the framework (dynamic or static) you are referencing you may need to consider a different approach.
Since you referenced the SOF thread - there seems to be a bug in Cordova which causes incorrect setup of custom plugins which reference dynamic frameworks. For example, all Cocoa Touch dynamic frameworks should be added as embedded binaries, that's why I it is advised to use the embed="true" attribute. However there is an issue on the official bug tracking system of Apache Cordova about similar cases.
Eventually you may consider adding a static framework instead (you will not need the embed attribute anymore for this purpose).
I hope this helps.
Also, I am moving this to the AppBuilder forum section because it does not relate to the Telerik Backend Services iOS SDK.
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