I am using jayceecam/apns in app engine golang api for sending push notification for iOS device. It works fine for some devices. For others it results INVALID_TOKEN error. If the device token is saved by common procedure for two different device, it works on one, but does not works for the other. Is there any iOS version related issue? library issue? or is anything wrong with the certificate.
Can anyone help me?
The library you're referencing has not been updated since Aug 2015, and the library that it was forked from (also not updated since 2015) has a github issue asking how could it be used on App Engine.
I would suggest a more active and updated library to handle APNs (here are some alternatives), although some indicate further issues when using this from GAE.
If you want to do this, dig into the library you're importing, check the open issues, and try to find a library that specifically claims to be supported in GAE.