When developing iOS applications for iPhone/iPad, is it necessary to register to the iOS Developer Program?
Yes, normally it is necessary to register to the iOS Developer Program in order to develop iOS applications. Actually, in iOS app development, it is not necessary to register the Mac environment to the iOS Developer Program, but you need to register to the program in order to install the developed application on an actual device and make it run.
The application that was developed using Monaca does not function well on mobile device.
In this case, please run and check the application again after stopping all the applications running on the device.
I can't successfully build iOS (iPhone/iPad) applications.
When developing iOS applications, you need to follow the instructions provided by Apple. Register properly the information of the device and developer, and then prepare the necessary files. For a step-by-step guide, please refer to Building an iOS App.
I was able to build iOS (iPhone/iPad) apps before, but now I can't do it anymore.
This may caused by the expiry of certificates, reissuing certificates requirement or other factors. Therefore, you need to recreate the provisioning profiles. Please recreate the required files like certificates and provisioning profiles by using the same procedures as before, and then use the new files. You may read about Generate Certificates and Create Provisioning Profiles for more details.
How to build iOS apps or manage certificates-related procedures?
Yes, you can share your Android KeyStore. You can download your Android KeyStore from Monaca Cloud IDE. Please always back up and keep the KeyStore that is used to sign application(s) because when a KeyStore is lost, it is impossible to use the same key to re-sign a signed package.