I want to develop QR Code App using python which support android and IOS . pl guide me on this.
Python is not a terribly common language for writing native mobile apps in, and it would likely be much easier using something like React Native. But if you really want to pursue this, Kivey and BeeWare are the two main frameworks.
This should be almost trivially easy: add a bar code reader library on top of the framework, should only really need one screen. Again, going back to Python not being a common native development platform means you may possibly have issues with libraries being functional cross OS versions + with support, but I don’t have any experience with using Python for mobile so can’t really comment further.