https://twitter.com/the_uhooi/status/1773739603591336289

RefreshablePlayground.swift

import SwiftUI

struct ContentView: View {
    @StateObject private var object = Object()
    
    var body: some View {
        List(object.numbers, id: \.self) { number in
            Text("Content \(number)")
        }
        .refreshable {
            await object.update()
        }
    }
}

final class Object: ObservableObject {
    @MainActor @Published var numbers: [Int] = [0]
    
    func update() async {
        try? await Task.sleep(for: .seconds(1))
        await addNewNumber()
    }
    
    @MainActor
    private func addNewNumber() {
        numbers.append(Int.random(in: 0..<100))
    }
}

Object.update() に処理をつっこんで、Task を作るパターン

（これは 下に引っ張って更新 するとアニメーションが消えちゃう）

import SwiftUI

@MainActor
final class Object: ObservableObject {
    @Published var numbers: [Int] = [0]
    
    nonisolated func update() async {
        Task { @MainActor in
            numbers.removeAll()
        }
        try? await Task.sleep(for: .seconds(1))
        Task { @MainActor in
            numbers.append(Int.random(in: 0..<100))
        }
    }
}

struct ContentView: View {
    @StateObject private var object = Object()
    
    var body: some View {
        NavigationStack {
            List(object.numbers, id: \.self) { number in
                Text("Content \(number)")
            }
            .refreshable {
                await object.update()
            }
        }
    }
}

Task.sleep(for:tolerance:clock:) のエラーを無視しないパターン

import SwiftUI

@MainActor
final class Object: ObservableObject {
    @Published var numbers: [Int] = [0]
    
    nonisolated func update() async {
        Task { @MainActor in
            numbers.removeAll()
        }
        do {
            try await Task.sleep(for: .seconds(1))
            Task { @MainActor in
                numbers.append(Int.random(in: 0..<100))
            }
        } catch {
            print(error)
        }
    }
}

struct ContentView: View {
    @StateObject private var object = Object()
    
    var body: some View {
        NavigationStack {
            List(object.numbers, id: \.self) { number in
                Text("Content \(number)")
            }
            .refreshable {
                await object.update()
            }
        }
    }
}

Task.value を await するパターン

import SwiftUI

@MainActor
final class Object: ObservableObject {
    @Published var numbers: [Int] = [0]
    
    nonisolated func update() async {
        await Task { @MainActor in
            numbers.removeAll()
        }.value
        try? await Task.sleep(for: .seconds(1))
        await Task { @MainActor in
            numbers.append(Int.random(in: 0..<100))
        }.value
    }
}

struct ContentView: View {
    @StateObject private var object = Object()
    
    var body: some View {
        NavigationStack {
            List(object.numbers, id: \.self) { number in
                Text("Content \(number)")
            }
            .refreshable {
                await object.update()
            }
        }
    }
}

struct Quote: Codable, Identifiable {
    let text: String?
    let author: String?
    
    var id: String {
        text ?? ""
    }
}

メインスレッドをパンパンにして 画面描画にも影響させるコード

import Foundation
import SwiftUI

func unsafeSleep() {
    for n in 0..<Int.max {
        _ = sin(Double(n))
    }
}

@MainActor
final class Object: ObservableObject {
    @Published var numbers: [Int] = [0]
    
    func update() async {
        Task { @MainActor in
            numbers.removeAll()
        }
        do {
            // try await Task.sleep(for: .seconds(1))
            unsafeSleep()
            Task { @MainActor in
                numbers.append(Int.random(in: 0..<100))
            }
        } catch {
            print(error)
        }
    }
}

struct ContentView: View {
    @StateObject private var object = Object()
    
    var body: some View {
        NavigationStack {
            List(object.numbers, id: \.self) { number in
                Text("Content \(number)")
            }
            .refreshable {
                await object.update()
            }
        }
    }
}

struct ContentView: View, Equatable {
    static func == (lhs: ContentView, rhs: ContentView) -> Bool {
        true
    }
    @StateObject private var exploreVM = ExploreViewModel()
}

適切かちょっと怪しいけど、再描画を期待していない冗長な更新がきっかけでbodyの再描画が起きてしまうことを防ぐなら