Is the cross plate form a better technique than pure Android or IOS?

It depends.

Native development costs more, but it has the following advantages:

- Make use of newer features

- Keep user experience

- Best performance

- Development tools are better

Choose cross-platform if:

- You want to develop for multiple platforms quickly.

- You can provide a nice UI.

the best way to develop mobile App is the native code.

but if you need other tools now you can use Visual studio community 2015 it is cross plate form

it mean you can write shared code and run it in Android , IOS and windows phone