Austin's Nerdy Things

Is Swift too concise for beginners?

This is not the first time I’ve tried to learn Swift. The first go took place maybe October/November 2020. I followed the official Apple Landmarks tutorial (called Creating and Combining Views) and things just did not click. I looked elsewhere for tutorials as well. My wife and I also had our first 3 month old around so my brain wasn’t functioning 100%. Regardless, I could follow the Landmarks tutorial, but not really step out on my own. The words I used to describe Swift to myself were “too cute” and “nuanced” and other things like that. After watching the Stanford CS193p Spring 2021 Lecture 3 video, there was a 2 minute section that really cleared things up for me. My background is mostly C# with some Python so that’s where I’m coming from.

Shortening things up

At 1:33:43 in the lecture, Professor Hegarty is finished taking two completely reasonable functions and chopping out more than half the characters. The resulting combination functions exactly the same as the two larger functions.

Before:

func makeCardContent(index: Int) -> String {
    return "A"
}
private var model: MemoryGame<String> =
    MemoryGame<String>(numberOfPairsOfCards: 4, createCardContent: makeCardContent)

Middle:

private var model: MemoryGame<String> =
    MemoryGame<String>(numberOfPairsOfCards: 4, createCardContent: {(index: Int) -> String in
        return "A"
    })

After:

private var model: MemoryGame<String> =
    MemoryGame<String>(numberOfPairsOfCards: 4) { _ in "A" }

The theme of the code reduction is ‘taking out things that Swift already knows’ as well as the ‘if this is the last argument of a function, plop the function in its place’. Let’s examine that for a minute.

The last argument of a function thing is really an if-then that you need perform mentally while writing code. When learning a language, it isn’t particularly easy to figure out what’s going on when all the code snippets are already fully reduced. Maybe I missed a key page in the documentation, but this wasn’t made clear to me in any of the learning I attempted to do. It could also just be that I don’t understand how functional programming is supposed to work.

That same code in C# (at least for the versions I use) would be a lot more clear to read. Everything would be specified, unless you precede a variable with var, which indicates that you want the compiler to infer the type. Being able to decide is nice.

When does concise become confusing?

All that said, I still think “cute” and “nuanced” are appropriate for describing Swift (at least SwiftUI). It tries to be cute by cutting out thing where other languages just leave them in. The underbar (_) when you don’t need to specify an argument is another example of this. Why not just make every argument label optional unless specifically called out as necessary?

The other thing is the mix between Swift being a strongly-typed language as well as type inferencing. If it is strongly-typed, we should need to specify the type basically everywhere. Leaving out the types and letting the compiler inference them seems to work really well (I know the compilers are all much smarter than me) but it doesn’t help readability.

Conclusion

Are these valid criticisms? I don’t know. If a Swift expert wants to watch me (via screensharing) work on some basic cryptocurrency tracking app I have going for 30-60 minutes to answer my questions and help me learn Swift (I would pay $$$!), I would love that. Swift will make more sense the more I write it, I know that, but I’m left wondering if I’ll always have these thoughts. Beautiful Swift is indeed beautiful. I just need to figure out how to get there.

Coming from Learning Swift (the programming language), I have completed Assignment 1 (including extra credit #1, but not #2). Most of the tasks were relatively straight-forward. I did not do any of the reading.

The last post had a fully functional game working as described in lectures 1 & 2. This assignment built from that.

Some brief notes on the required tasks:

1. Easy. Done on the last post.
2. Also easy.
3. Not too hard, just added a new struct called TitleView and plopped it before the ScrollView in the VStack
4. I tried to figure out a way to have the emojis var populated with the contents of a different emoji list (e.g. vehicleEmojis, as in var emojis = vehicleEmojis), but wasn’t successful. This will probably be covered in lecture 3. I ended up just hardcoding the initial list to be the same values as the vehicleEmoji string array. The buttons themselves were pretty straightforward.
5. The hardest part about this was figuring out how to use the emoji browser so I didn’t have to close and re-open it for every new emoji. I did vehicles, animals, and fruit.
6. array.shuffled(), easy
7. VStack the system images with text
8. Okay, I suppose I can do that. I picked the fruit emojis before realizing there weren’t specific fruit symbols. In SF 2, there is a leaf, which is close enough. This seems a bit nit-picky.
9. font(.body)
10. ok

Extra credit:

1. set emojiCount to be a random value from 4 (minimum specified in the task) up to yourEmojiListVar.count. easy. do this after shuffling though
2. this seems like a lot of work for something I don’t really need to do yet

Code

//
//  ContentView.swift
//  Memorize - Stanford CS193p, Spring 2021
//  After assignment 1
//
//  Created by Austin from austinsnerdythings.com on 5/27/21.
//

import SwiftUI

struct ContentView: View {
    var vehicleEmojis = ["?","?","?","?","?","?","?","?","?","?","?","?","?","✈️","?","?","?","?","?","?","?","?","?","?"]
    var animalEmojis = ["?","?","?","?","?","?","?","?","?","?","?","?"]
    var fruitEmojis = ["?","?","?","?","?","?","?","?","?","?","?","?"]
    
    @State var emojis = ["?","?","?","?","?","?","?","?","?","?","?","?","?","✈️","?","?","?","?","?","?","?","?","?","?"]
    @State var emojiCount: Int = 8

    var body: some View {
        VStack {
            TitleView()
            ScrollView {
                LazyVGrid(columns: [GridItem(.adaptive(minimum: 80))]){
                    ForEach(emojis[0..<emojiCount], id: \.self) { emoji in
                        CardView(content: emoji)
                            .aspectRatio(2/3, contentMode: .fit)
                    }
                }
            }
            .foregroundColor(.red)
            Spacer()
            HStack {
                vehicleTheme
                Spacer()
                animalTheme
                Spacer()
                fruitTheme
            }
            .font(.largeTitle)
            .padding(.horizontal)
        }
        .padding()

    }
    
    var remove: some View {
        Button {
            if emojiCount > 1 {
                emojiCount -= 1
            }
        } label: {
            Image(systemName: "minus.circle")
        }
    }
    
    var add: some View {
        Button {
            if emojiCount < vehicleEmojis.count {
                emojiCount += 1
            }
        } label: {
            Image(systemName: "plus.circle")
        }
    }
    
    var vehicleTheme: some View {
        Button(action: {
            emojis = vehicleEmojis.shuffled()
            emojiCount = Int.random(in: 4..<vehicleEmojis.count)
        }, label: {
            VStack{
                Image(systemName: "car").font(.largeTitle)
                Text("Vehicles").font(.body)
            }
        })
    }
    var animalTheme: some View {
        Button(action: {
            emojis = animalEmojis.shuffled()
            emojiCount = Int.random(in: 4..<animalEmojis.count)
        }, label: {
            VStack{
                Image(systemName: "hare").font(.largeTitle)
                Text("Animals").font(.body)
            }
        })
    }
    var fruitTheme: some View {
        Button(action: {
            emojis = fruitEmojis.shuffled()
            emojiCount = Int.random(in: 4..<fruitEmojis.count)
        }, label: {
            VStack{
                Image(systemName: "leaf").font(.largeTitle)
                Text("Fruits").font(.body)
            }
        })
    }
}

struct CardView: View {
    var content: String
    @State var isFaceUp: Bool = true
    
    var body: some View {
        ZStack {
            let shape = RoundedRectangle(cornerRadius: 20)
            if isFaceUp {
                shape.fill().foregroundColor(.white)
                shape.strokeBorder(lineWidth: 3)
                Text(content).font(.largeTitle)
            } else {
                shape.fill()
            }
        }
        .onTapGesture {
            if isFaceUp == true {
                isFaceUp = false
            } else {
                isFaceUp = true
            }
        }
    }
}

struct TitleView: View {
    var body: some View {
        HStack {
            Spacer()
            Text("Memorize!").font(.largeTitle)
            Spacer()
        }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
            .preferredColorScheme(.light)
        ContentView()
            .preferredColorScheme(.dark)
    }
}

Screenshots

Next up – lecture 3

Link to post about lecture 3 here.