define a uiview and set its size and position as well as its background colour to red in swift

To define a UIView in Swift and set its size, position and background color, you first need to create an instance of the UIView class. Then, you can set its properties by changing its frame and backgroundColor properties.

main.swift
// Create a new UIView instance
let myView = UIView()

// Set the frame (position and size)
myView.frame = CGRect(x: 100, y: 100, width: 200, height: 200)

// Set the background color
myView.backgroundColor = UIColor.red
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After these lines of code have been executed, you will have a red square UIView with a width and height of 200 points, positioned 100 points from the left edge of the screen and 100 points from the top edge of the screen.