Different aspect ratios

Question

So how do you treat your different aspect ratios now we have iphone 4, 5 and 6 all different sizes?
Do you build for 4 and then have extra space and backgrounds for 5 and 6, or do you adjust your app based on the different resoltuons by detecting the res and auto adjusting and moving things?

Answer 1

The answer is it's up to you. What you're asking about is a design principle called 'Fluid Layout' or 'Responsive Layout'. The idea is to design your UI so it responds to the different resolutions and/or aspect ratios of the screen it's on.
Fluid layout is the term when the app continuously adjusts itself as the window is resize ( this is more of a desktop approach since mobile is on a fixed screen size ).
Responsive layout is when the UI jumps to a specific state when dimensional threshholds are reached. So you could have 4 different layouts ( Mobile, Tablet, Desktop, Extended Desktop ) that the app can switch among depending on the screen size dimensions. In your case you may want to take the mobile layout and break it up into aspect ratios.
Responsive layout is more easy to program and recommended for people new to the principle since it's easier to think of set states instead of constant flow. But Fluid Layout is the best solution if your an advanced developer because you never have to go back in and create a new state to support new devices. The layout is always perfect no matter the screen.
How it works programmatically you usually have a listener, very high up in the program, that watches for the stage resizing and then calls a function that tells the UI to realign itself and go through all the children so they know to realign themselves. In your case you could just run that on launch because your screen size should never adjust. In some cases you should update the children first then the parents.
Hope this helps.