Responsive font size in iOS for different resolutions?

Question

iOS

On iphone 5, iphone 5s, iphone 6 devices - the main font of the text looks good
On iphone 6+ devices with a much higher resolution - the same font looks already small and the layout does not look so
good + font size (but without developing for each individual resolution of their styles)?
Question 2: is it possible to use vector graphics for the same purposes - so as not to slip your bitmap image under each resolution?
Question 3: similar problems shine when developing an analogue for android. How are things with them?

Answer 1

1. there is a so-called Adaptive User Interface ,
that is, you not only need to change the font in a vacuum, but also other UI elements, indents, margins, etc. Here is a good tutorial for iOS programmers, but a designer can also get acquainted and understand what is happening.
2. Vector graphics can be used and no dances with different sizes are needed, here you can see my answer and comments below it.
3. There are also problems there, but you probably better off with someone from there.