How can I make all elements of a view be entered proportionally to the screen(xCode 6, using swift)?

All the screens you listed are of the same type. Your app will look the same on all the screens of the same type, without extra work. However, that's not the end of the story.

There are really only two screen types for iOS. The first one includes all iPhones before and including iPhone 4 and iPads. Another type includes only iPhones 5+. You are supposed to support both types in your application. In fact, Apple will not let you publish an app that doesn't look good on both screen types - hence the requirement to provide screen shots for both 3.5' and 4' screens - which represent each type. In addition, you need to make sure the app runs fine on an iPad, even if you don't plan on supporting iPads specifically. All apps for iPhones should run on iPads but if the app is made specifically for an iPad it's not required to work on an iPhone/iPod.

What this means is this - if you use Storyboard with AutoLayout, emulating an iPhone 5+ screen type and dont define proper constrains manually you will literally loose bottom part of the screen without any errors or anything when the app is ran on an earlier iPhone (like, iPhone 4s which also got the iOS 8 update) or an iPad. It will just get cut-off.

You should use AutoLayout to define constrains between screen bounds and elements themselves. You have two options on how to handle difference is the screen height:

1. One or more elements have flexible heights to make sure they stretch to fill up extra spaces for iPhones 5+ while also looking fine on iPhones <= 4 and iPads. This will require you to define vertical space between the top of the screen, all elements from the top to the bottom, and the bottom of the screen. Define height constrains for elements you do not want to stretch. This is also the proper way to use AutoLayout with scroll views.
2. Or anchor one or more element to the top or bottom of the screen, and specify vertical constrains to elements below/above it. You will need to specify the heights for all elements if you want to do it this way.

Once you start specifying constrains manually on Storyboard, XCode will try and assist you by letting you know if it needs more constrains or you're good to go. Lack of warnings is a good indicator that you are on the right path.

Define constrains by pressing Crtl + Left Mouse click on an element, then drag the mouse towards the direction of constraint. You might want to do a simple tutorial to figure this out.