Cocoa versus Cocoa Touch - What is the difference?

Question

I am learning iOS development in Objective-C, and I have found a lot of code examples.

Some of them, though, say that they are only for Mac OS X (not iOS).

C

Answer 1

In term of import in Swift

import Cocoa in Mac OSX application is the same as

import AppKit
import CoreData
import Foundation

whereas we can't import CocoaTouch in iOS