Please Open an Issue If You See Something Here You'd Like Explained Better - I am still editing these files and these pages are not in a final form. Any other encouragement would be welcome as well! 🙏🏻
There's a lot of Swift 101 style information available online. The thing is, Swift is a very powerful language and new features are constantly emerging and evolving. For a developing technician it can be daunting to move from novice to intermediate programmer. StackOverflow is a wonderful resource if you know what you need to ask for and formulate your question well. Reddit can provide you with some fleeting moral support. Twitter has lots of busy people drifting in and out. So how to navigate your way as a budding developer?
In the process of preparing for an upcoming interview, I stumbled across an old gem, an algorithm called Flood Fill. (See links below)
It’s a simple concept, and the resulting code is fairly compact, but it takes a few minutes to wrap your head around. You may not have a few minutes during an interview, so it’s best to get a heads up by digesting the concept and potential solutions. So I decided to take it one step further, and code an animation of the flood fill algorithm. The result is what you find here.
Typically the algorithm is described in a slightly abstract, mathematic way, but I’m a fan of color. So I’m going to present how it works graphically.
Starting with a randomized grid of colors, click on any cell. In a flood fill, the square underneath the cursor will flip color, and any adjacent cells (vertical, horizontal, not diagonal) of the same color are flipped as well.
Those old-timers reading this can spot the similarity with Conway’s “Life” animation (links below) where a cell value is updated depending on the state of a neighboring cell.
You can solve this problem iteratively or using recursion, and of course the interviewer may tell you which is expected of you. So be prepared to solve it both ways.
I’ll have a bit more to say about the algorithm in the next link, but I want lay out a plan for what I expect to cover here.
This page. A description of our journey ahead.
A parable to serve as an introduction to recursion.
Is this the meat and potatoes of the project?
When you tell the compiler more about your data structures it can make your life easier. [this is a stub]
- Bindings are what make SwiftUI so magical, and property wrappers make it easier for you to use them.
- An overview of how bindings provide two way communication.
- Brief discussion of @State, @StateObject, @ObservedObject
We're going to take your new found knowledge of bindings to a whole new level!
[this is a stub]
It's a giant step from bindings to the world of TCA.
Functional Programming principles guide a structured approach to updating your data and having your Views update themselves automatically.
Pickers and a couple of taps.
I review a simple (but complete) State/Action/Environment/reducer setup using .binding() and the more traditional .send()
The discussion has been kept simple, and I’ve tried to help connect the how or why when explaining the relationships between the individual lines of code and the architecture of the system.
For anyone who finds this sample/tutorial trivial, I have a challenge for you! I have yet to complete a version that animates correctly using the recursive algorithm. I describe the problem I encountered below. Please open an issue and paste a code snippet if you are able to get a sequential animation of the cells using a recursive algorithm (it doesn’t have to be the one I used…) I will edit this page explaining the addition so everyone can benefit from your contribution.
I opened two questions on StackOverflow related to the issues encountered, and I can open more.
I write almost all of my code in modules (Swift Packages using the Swift Package Manager). Without the public access modifier the code would not be visible outside the package, which means it can’t be called from outside the package. This is because the default access level in Swift is internal.
Each module specifies a namespace and enforces access controls on which parts of that code can be used outside of the module.
I’ll have more to say about namespaces in another project. Here’s a couple of links in case you’re curious:
You can probably skip the access modifier if all your code is in the one Xcode project you’re working on, but be aware that if you declare a protocol public, then you will see a cascading effect as the compiler enforces consistency. You have probably seen this if you have declared a View as public. The View protocol requires that a public View has a public init and a public body.
You probably already knew this, although may not have known why.
I am grateful to the many people online who contribute to the Swift Community in so many ways. Here is a partial list of the people and organizations that have made my journey more exciting and perhaps a bit less bumpy.
Swift Forums
Apple Developer Forums
GitHub
StackOverflow
HackingWithSwift (Paul Hudson)
Pointfree
SwiftBySundell
SwiftTalk
Asperi (StackOverflow)
Erica Sadun
John Sundell - Twitter
Majid
martin-r (StackOverflow)
Natasha the Robot - Twitter
rmaddy (StackOverflow)
Rob (StackOverflow)
Rob Mayoff (StackOverflow)
vacawama (StackOverflow)
I urge you to visit these sites, patronize and contribute where you can, become a contributor to the community as well!
LearnAppMaking.com
Nathan Gitter - Pentatonic
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