Secure my ionic app

hello , i already finished my app , So How can add security features in ionic and
how can I secure it ?

Your question is extremely broad, but in general the time to think about security is before you write a single line of code. Make a list of attack vectors - things you would not want to happen. Then consider how you would eliminate each one. You must always remember that if you don’t trust the owner of the device, nothing in your app binary is secret. The only place you can enforce constraints is on servers under your control. If, of course, the app has no network activity, then there isn’t really anything you can secure.