eecsreactive

// UM EECS 441
import UIKit

final class MainView: UIView {
    var counter: UILabel!
    private var addOne: UIButton!

    required init?(coder: NSCoder) {
        fatalError("MainView: does not support unarchiving view from xib/nib files")
    }

eecsreactive

// UM EECS 441
class MainView(context: Context): ConstraintLayout(context) {
    val counter: TextView
    val addOne: Button

    init {
        counter = TextView(context).apply {
            textSize = 44.0f
            id = generateViewId()
        }

eecsreactive

// UM EECS 441

class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        setContent {
            var count by remember { mutableStateOf(0) }

            Column(horizontalAlignment = Alignment.CenterHorizontally,

eecsreactive

// UM EECS 441
import SwiftUI

struct ContentView: View {
    @State var count = 0
    
    var body: some View {
        VStack {
            Text("\(count)")
            Button("+1", action: { count += 1 } )

eecsreactive

// UM EECS Reactive

import SwiftUI

struct ChildView: View {
    let count: Int // new state if @State
    var body: some View {
        Text("\(count)")
    }
}

eecsreactive

// UM EECS Reactive

import SwiftUI

struct ChildView: View {
    @Binding var count: Int
    var body: some View {
        Button("+1") { count += 1 }
    }
}

eecsreactive

// UM EECS 441

import SwiftUI
import Observation

@Observable
final class RefCounter {
    var count = 0
    //@ObservationIgnored 
    var name = "even"

eecsreactive

// UM EECS 441

import SwiftUI
import Observation

@Observable
final class RefCounter {
    var count = 0
    var name = "counter"
}

eecsreactive

// UM EECS 441

import SwiftUI
import Observation

@Observable
final class RefCounter {
    var count = 0
    var name = "counter"
}

eecsreactive

// UM EECS Reactive

import SwiftUI

@main
struct StateValueApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
                // #1: comment out for optional