With the release of iOS11, Apple released the Xcode 9 to the public. Here are some of the new features that they’ve added. 1- New Simulator Apple added a new simulator to Xcode 9, including a home button for iPhone 8 and below, and well as the ability to touch and use the physical buttons …
NS stands for NextStep, Which is the company created by Steve Jobs after he was fired from Apple in 1985. After Jobs came back to Apple, he brought the technology he created at NextStep with him which became later a naming convention for all the classes in Objective-C. For example, NSString, NSURL, and NSArray.
I recently came across an interesting article talking about the @2x image in iOS. So to summarize that, if your app supports both retina and non-retina displays then you should include on image with a regular size for the non-retina display (ex. backImage.png) and another one with higher resolution for the retina display (ex. backImage@2x.png).