Memo

SwiftUI+Timer

【Combine】Timerの処理をCombineを使って置き換える - Swift・iOS
https://www.hfoasi8fje3.work/entry/2021/08/22/%E3%80%90Combine%E3%80%91Timer%E3%81%AE%E5%87%A6%E7%90...

ContentView.swift
import SwiftUI

struct ContentView: View {
    @ObservedObject private var viewModel = TimerModel()

    var body: some View {
        VStack {
            Text("\(viewModel.count)")
                .font(.title)
                .fontWeight(.bold)
                .padding()

            if viewModel.count <= 0 {
                Text("終了").padding()
            } else if viewModel.isTimerRunning {
                if (viewModel.count <= 3) {
                    Text("もうすぐ終了").padding()
                } else {
                    Text("カウントダウン中").padding()
                }
            } else {
                Text("ストップ中").padding()
            }

            Button("Start") {
                viewModel.startCounting()
            }
            .disabled(viewModel.isTimerRunning)

            Button("Stop") {
                viewModel.stopCounting()
            }
            .disabled(!viewModel.isTimerRunning)
            .padding()

            Button("Reset") {
                viewModel.resetCount()
            }
        }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
            // プレビュー表示のために必要
            //.environmentObject(TimerModel())
    }
}


TimerModel.swift
import Foundation
import Combine

class TimerModel: ObservableObject {
    @Published var count = 10
    @Published var isTimerRunning = false

    private var cancellable: AnyCancellable?

    func startCounting() {
        isTimerRunning = true
        cancellable = Timer.publish(every: 1.0, on: .main, in: .common)
            .autoconnect()
            .sink { _ in
                if self.count <= 0 {
                    self.stopCounting()
                } else {
                    self.count -= 1
                }
            }
    }

    func stopCounting() {
        isTimerRunning = false
        cancellable?.cancel()
    }

    func resetCount() {
        count = 10
    }
}
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