Book Image

Swift 2 By Example

By : Giordano Scalzo
Book Image

Swift 2 By Example

By: Giordano Scalzo

Overview of this book

Swift is no longer the unripe language it was when launched by Apple at WWDC14, now it’s a powerful and ready-for-production programming language that has empowered most new released apps. Swift is a user-friendly language with a smooth learning curve; it is safe, robust, and really flexible. Swift 2 is more powerful than ever; it introduces new ways to solve old problems, more robust error handling, and a new programming paradigm that favours composition over inheritance. Swift 2 by Example is a fast-paced, practical guide to help you learn how to develop iOS apps using Swift. Through the development of seven different iOS apps and one server app, you’ll find out how to use either the right feature of the language or the right tool to solve a given problem. We begin by introducing you to the latest features of Swift 2, further kick-starting your app development journey by building a guessing game app, followed by a memory game. It doesn’t end there, with a few more apps in store for you: a to-do list, a beautiful weather app, two games: Flappy Swift and Cube Runner, and finally an ecommerce app to top everything off. By the end of the book, you’ll be able to build well-designed apps, effectively use AutoLayout, develop videogames, and build server apps.
Table of Contents (18 chapters)
Swift 2 By Example
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
Free Chapter
1
Welcome to the World of Swift
2
Building a Guess the Number App
Index

Blurring the background


The first naïve idea would be to change the level of blurriness depending on the position of scrollView, but this will be really inefficient because the blur operation is CPU-intensive, and it won't be smooth on older devices.

So, the idea is to trick the user. Instead of blurring the image at every change of position of scrollView, we blur the image, only before setting it to UIImageView. Then, we set the alpha channel to 0 (which means transparent). Next, we change the alpha depending on the position, reaching opaque when the scrollView offset reaches half.

First of all, we need to import the framework to blur the image:

import FXBlurView

Then, we need to create the overlay view and set it as subview:

private let overlayView = UIImageView()
//...
func setup(){
    //...
    overlayView.contentMode = .ScaleAspectFill
    overlayView.clipsToBounds = true
    view.addSubview(overlayView)
    //...
    scrollView.delegate = self
    view.addSubview(scrollView)
}
func layoutView...