我是 CoreData 的新手，但我创建了一个对象，打算在 SwiftUI 中的 ForEach 循环内使用该数组。
在实体编辑器中，我添加了一个 UUID 属性stored_id。然后在扩展中我写了以下内容：
extension Item: Identifiable {
public var id: UUID {
guard let stored_id else {
assertionFailure("No stored ID")
return UUID()
}
return stored_id
}
}
我觉得这很奇怪，原因有很多，比如根据 CoreData 的语义，stored_id 是可选的。出于某种原因，这难道不是不好的做法吗？
我到处搜索但似乎找不到这个问题的明确（当前）答案。
出于无障碍考虑，我设置了一个 UILabel，使用动态字体大小调整。使用以下代码运行效果很好：
attributes[.font] = UIFont.preferredFont(forTextStyle: .body)
但是，从设计的角度来看，默认字体对我来说不起作用。
当我尝试使用自定义字体时，通过执行以下操作：
attributes[.font] = UIFont(name: "Futura-Medium", size: 17)
它迫使我定义大小，我相信这会覆盖动态更改字体的能力。
我很想找出两个解决方案中的其中一个......
要么将 preferredFont 定义为我选择的通用字体。要么写一行更好的代码，让我可以选择自定义字体，并且仍然可以动态调整。
回顾一下...目前我的结果要么是正确缩放文本，要么是带有以下代码的通用字体：
var attributes = [NSAttributedString.Key: Any]()
attributes[.font] = UIFont.preferredFont(forTextStyle: .body)
attributes[.foregroundColor] = UIColor.black
或者它是一种更合适的字体，但根本无法通过此代码缩放：
var attributes = [NSAttributedString.Key: Any]()
attributes[.font] = UIFont(name: "Futura-Medium", size: 17)
attributes[.foregroundColor] = UIColor.black
有一个用于读写字典数据的数据存储。我使用了一个全局 Actor，它可以保证操作的串行执行。
代码示例：
@globalActor
struct DataStorageActor {
actor ActorType { }
static let shared: ActorType = ActorType()
}
@DataStorageActor
class CustomDataStorage {
private var storage: [String: String] = [:]
func write(key: String, value: String) async throws {
print("\(Date()): Write started")
try await Task.sleep(nanoseconds: 5_000_000_000)
storage[key] = value
print("\(Date()): Write completed for key: \(key)")
}
func read(key: String) async throws -> String? {
print("\(Date()): Read started")
let value = storage[key]
print("\(Date()): Read completed for key: \(key)")
return value
}
}
并编写了一个单元测试：
@Test(arguments: ["Very long string"])
func testSerialExecution(input: String) async throws {
let storage = CustomDataStorage()
let task1 = Task {
try await storage.write(key: "test", value: input)
}
let task2 = Task {
try await Task.sleep(nanoseconds: 2_000_000_000)
let value = try await storage.read(key: "test")
print("\(Date()): Received value: \(value ?? "nil")")
return value
}
print("wait task 1")
_ = try await task1.value
print("wait task 2")
let value: String? = try await task2.value
print("check result")
#expect(value == input)
}
但读取操作是并行运行的，记录如下：
wait task 1
2025-04-07 12:43:03 +0000: Write started
2025-04-07 12:43:05 +0000: Read started
2025-04-07 12:43:05 +0000: Read completed for key: test
2025-04-07 12:43:05 +0000: Received value: nil
2025-04-07 12:43:08 +0000: Write completed for key: test
wait task 2
check result
为什么它会这样工作？
我有水平滚动的卡片，每个卡片可以有不同的高度。问题是 LazyHStack 会获取第一个项目的高度，但如果项目较大，该如何更改它呢？在滚动时更改高度也是可行的。我知道使用非惰性 HStack 可以解决这个问题，但需要 LazyHStack 的解决方案。
let items = ["Short", "Also short", "Short again", "But this is veeeery veeeery looong!"]
ScrollView(.vertical) {
VStack {
ScrollView(.horizontal) {
LazyHStack {
ForEach(0 ..< items.count) { index in
Text(items[index])
.frame(width: 150)
}
}
}
Text("Some static content here")
}
}
此代码显示了一个封面流样式视图，您可以在其中滚动浏览滚动视图中的图像，而图像本身来自数组。间距为 -100，以使不在屏幕中间的其他图片出现在当前图片后面。虽然这在左侧运行良好，但在当前图像的右侧，ScrollView 中的其他图像相交：（
纸飞机在中间，下载符号在它前面）
使用 zIndex，我希望在用户滚动浏览图库时动态更新视图。我尝试使用 GeometryReader 和 @State var selectedItemInd，但效果不佳，因为视图没有更新。我相信每次用户滚动时，我不仅需要知道哪个项目处于中间位置，还需要知道所有其他项目的位置。
import SwiftUI
import MusicKit
struct ContentView: View {
#if false
let images = ["Ghost - Single", "Burre - Single", "Butterfly 3001", "Tension (Deluxe)", "Shreya Ghoshal_ Best of Me", "Life - EP", "Liebeskummer lohnt sich nicht"]
#else
let images = ["externaldrive.fill.badge.checkmark", "square.and.arrow.up.fill", "square.and.arrow.up.circle", "folder.circle", "paperplane.fill", "square.and.arrow.down", "square.and.arrow.down.fill", "doc.badge.gearshape", "square.and.arrow.up.on.square.fill"]
let colours = [Color.red, Color.blue, Color.green, Color.yellow, Color.orange, Color.purple, Color.pink, Color.cyan, Color.indigo]
#endif
var itemWidthHeight: CGFloat = CGFloat(200)
@StateObject var albums = MusicStorage.shared
@StateObject var authorizationObject = AuthorizationHandler.shared
// @State var selectedItemInd: Int = 0
var body: some View {
VStack{
GeometryReader { geo in
ScrollView(.horizontal, showsIndicators: false){
HStack(spacing: -100) {
ForEach(0..<images.count) { s in
Image(systemName: images[s])
.resizable()
.aspectRatio(contentMode: .fit)
.frame(width: itemWidthHeight, height: itemWidthHeight)
.background(colours[s])
.visualEffect { effect, proxy in
let frame = proxy.frame(in: .scrollView(axis: .horizontal))
let distance = frame.minX
// print(distance)
return effect
//only rotate at left or right swipe, not both at once
// distance to left is negative, distance to right is positive value
.rotation3DEffect(Angle(degrees: distance < 0 ? min(-distance * 0.3, 40) : 0), axis: (x: 0.0, y: 1.0, z: 0.0))
.rotation3DEffect(Angle(degrees: distance > 0 ? max(-distance * 0.3, -40) : 0), axis: (x: 0.0, y: 1.0, z: 0.0))
}
// .frame(width: itemWidthHeight, height: itemWidthHeight, alignment: .center)
}
}
.scrollTargetLayout()
}
.frame(width: geo.size.width, height: geo.size.height, alignment: .center)
.contentMargins((geo.size.width / 2) - itemWidthHeight / 2) // scroll view item should be in middle position
.scrollTargetBehavior(.viewAligned(limitBehavior: .automatic))
}
}
.onAppear() {
albums.loadAlbums()
}
// Sheet is presented if authorization failed (init)
.sheet(isPresented: $authorizationObject.isSheetPresented) {
AuthorizationSheet(musicAuthorizationStatus: $authorizationObject.isAuthorizedForMusicKit)
.interactiveDismissDisabled()
}
}
}
#Preview {
ContentView()
}
但也许我错了，有一个简单的解决方案。有什么想法吗？
我有一个 SwiftUI 应用，它以列表形式显示带有帖子的社交信息流。每篇帖子都包含需要保持交互的按钮，但我不希望整个单元格都可点击。
我尝试了不同的方法，例如在列表上使用 .disabled(true)（也会禁用按钮）、在单个元素上使用 .allowsHitTesting(false) 以及使用 .onTapGesture {} 来吸收点击，但都无法按预期工作。
谢谢
List() {
ForEach(posts, id: \.self) { post in
PostView()
.onAppear {
if post == posts.last {
loadMorePost()
}
}
.listRowInsets(EdgeInsets())
.alignmentGuide(.listRowSeparatorLeading) { vd in
return 0
}
}
}
.listStyle(.plain)
struct PostView: View {
var body: some View {
VStack(spacing: 10) {
PostHeaderView(image: Image("clovis"), userName: "Stephane", userIdentifier: "stephane_")
PostContentView()
}
.padding(20)
}
}
struct PostContentView: View {
var body: some View {
VStack(alignment: .leading, spacing: 10) {
// Post content
Text("Coiffeuse")
.font(.headline)
Text("It is a long established fact that a reader will be distracted...")
.font(.caption)
HStack(spacing: 20) {
PriceContainerView()
Spacer()
HStack(spacing: 2) {
Image(systemName: "eyes")
Text("2K")
}
// This button needs to remain interactive
Button(action: { print("Save To Later") }) {
Image(systemName: "bookmark")
.foregroundStyle(.mediumGray)
}
}
}
}
}
```
我正在构建一个使用 Firebase 身份验证的 SwiftUI 应用，但在用户注销时遇到了导航问题。我的应用结构如下：
App.swift 中的根视图有条件地显示：如果未经身份验证则显示 WelcomeView，如果经过身份验证则显示 MainTabView
从 MainTabView 中，用户可以浏览多个嵌套的 NavigationLinks：
MainTabView → 设置（通过 NavigationLink）设置 → 帐户信息（通过 NavigationLink 或工作表）
帐户信息包含一个注销按钮当用户从深度嵌套的帐户信息屏幕注销时，Firebase 身份验证状态会正确更新（通过打印语句确认），但 UI 不会导航回 WelcomeView。
实施细节 使用 Firebase Auth 进行身份验证
我尝试 在 signOut 方法中明确设置 isAuthenticated = false
对 FireAuthManager 使用 @EnvironmentObject
尝试手动弹出到根目录（这在 SwiftUI 中效果不佳）
问题： 在使用深度嵌套的 NavigationLink 时，SwiftUI 中重置导航并在注销时返回欢迎屏幕的正确模式是什么？如何确保无论用户在导航堆栈中处于多深的位置，UI 都能正确响应身份验证状态的变化？
func signOut(comp: (Error?) -> Void) {
do {
try Auth.auth().signOut()
isProfileCompleted = nil
self.isAuthenticated = false
PresenceManager.shared.setOfflineOnLogout()
comp(nil)
print("User signed out successfully")
} catch let signOutError as NSError {
print("Error signing out: \(signOutError.localizedDescription)")
comp(signOutError)
}
}
NavigationStack {
Group {
if authManager.isAuthenticated == false {
WelcomeView()
} else {
MainTabView()
}
}
}
}
在以下 Swift 代码中：
import Foundation
struct MySet<T: Hashable>: CustomStringConvertible {
let set: Set<T>
}
extension MySet {
var description: String {
return "\(self.set)"
}
}
extension MySet where T: Comparable {
var description: String {
return "\(self.set.sorted())"
}
}
let intSet: Set<Int> = [6, 3, 4, 9, 12, 49, -1, 44, -1000, 1000]
let myIntSet = MySet(set: intSet)
print("myIntSet: \(myIntSet.description)")
print("myIntSet: \(myIntSet)")
print("myIntSet: ", String(describing: myIntSet))
我正在尝试创建一个自定义描述（针对 CustomStringConvertible 协议），该描述会根据集合中的元素是否可比较而有所不同。上面的输出是：
myIntSet: [-1000, -1, 3, 4, 6, 9, 12, 44, 49, 1000]
myIntSet: [9, -1, 3, 1000, 6, 4, 12, 44, 49, -1000]
muIntSet: [9, -1, 3, 1000, 6, 4, 12, 44, 49, -1000]
如您所见，如果我显式打印myIntSet.description，我会得到所需的输出，即排序列表。但如果我在结构本身上使用字符串插值，或者String(describing: myIntSet)，我会从第一个（无条件）扩展中获得描述。
有人能解释为什么会发生这种情况吗？如何获取字符串插值并String(describing: ...)使用所需的描述？
我正在尝试重新创建此背景图像的图案，它看起来像云。有没有办法使用 SwiftUI 以编程方式完成此操作？
我知道如何添加渐变和颜色，图像文本和按钮也一样，但我不知道我是否可以通过编程获取图案，或者我是否必须获取此类图案的资产。我应该只获取图片吗？
我又犯了一个可能又愚蠢的错误。目前的问题是这样的。我正在使用 Apple 的 MKLocalSearchCompleter 获取餐厅的名称和地址。我还使用 SwiftData 存储所有内容。我在表单上显示了一个表单。在调用表单之前，varsity 显示正确的占位符文本。在这种情况下，“tacos”表示餐厅名称，“bell”表示地址。单击位置按钮后，您可以搜索并点击您想要的那个。点击按钮正在更新 review.resataurantName 和 review.location，因为我已将它们打印到控制台。但是它不会更新表单中的值。以下是我认为与该问题相关的代码。
以下是编辑餐食视图
import SwiftUI
import PhotosUI
import SwiftData
struct EditMealView: View {
@Binding var isPresentingNewMealView: Bool
@Environment(\.modelContext) private var modelContext
@State var mealImage: Image? = nil
@State private var selectedItem: PhotosPickerItem? = nil
@Bindable var review: Review
@State private var imageData: Data?
@State var selection: TextSelection? = nil
@State private var locationService = LocationService(completer: .init())
@State private var search: String = ""
@State private var isPresentingLocationView = false
// @State var chosenLocation: String? = AddressView($locationSubtitle)
let foodTypeList: [String] = ["Select One...", "Fast Food", "Vegetarian", "Central African", "East African", "North African", "Southern Africa", "West African", "Latin American", "Native American", "Canadian", "Carribean", "Mexican", "American", "Southern American", "Fusion", "Central American", "South American", "Chinese", "Japanese", "Korean", "Indian", "Middle Eastern", "Thai", "Turkish", "Vietnamese", "Italian", "French", "German", "Spanish", "Greek", "Romanian", "Russian", "Eastern European", "Scandinavian", "British", "Dutch", "Swedish", "Norwegian", "Icelandic", "Irish", "Polynesian", "Australian", "New Zealand", "Other"]
var body: some View {
NavigationStack {
ZStack {
LinearGradient(gradient: Gradient(colors: [Color(red: 0.9725490196078431, green: 0.9607843137254902, blue: 0.8627450980392157, opacity: 1), Color(red: 0.9137254901960784, green: 0.9254901960784314, blue: 0.8509803921568627, opacity: 1), Color(red: 0.9882352941176471, green: 0.7529411764705882, blue: 0.13333333333333333, opacity: 1), Color(red: 0.9450980392156862, green: 0.47058823529411764, blue: 0.08627450980392157, opacity: 1)]), startPoint: .top, endPoint: .bottom).ignoresSafeArea()
.navigationTitle("Add Meal")
VStack{
Form {
TextField("Menu Item", text: $review.foodName)
.listRowBackground(Color.clear)
.autocorrectionDisabled()
HStack {
Button(action: {isPresentingLocationView = true}
) {
Text("Location")
Image(systemName: "map")
}
.sheet(isPresented: $isPresentingLocationView) {
AddressView(isPresentingLocationView: $isPresentingLocationView, review: Review(foodName: "", restaurantName: "", location: "muncie", rating: 3, foodImage: nil, foodType: "", reviewNotes: "")//, //restaurantName: ""
)
}
VStack {
Text("\(review.restaurantName)")
.listRowBackground(Color.clear)
.autocorrectionDisabled()
Text("\(review.location)")
.listRowBackground(Color.clear)
.autocorrectionDisabled()
}
}
.listRowBackground(Color.clear)
Picker(selection: $review.foodType, label: Text("\(review.foodType)")) {
ForEach(0..<foodTypeList.count, id: \.self) {
Text(self.foodTypeList[$0])
.tag(self.foodTypeList[$0])
}
}
.listRowBackground(Color.clear)
HStack{
Spacer()
RatingView(rating: $review.rating)
.multilineTextAlignment(TextAlignment.center)
Spacer()
}
.buttonStyle(.plain)
.listRowBackground(Color.clear)
if let imageData = review.foodImage, let uiImage = UIImage(data: imageData) {
Image(uiImage: uiImage)
.resizable()
.scaledToFit()
}
PhotosPicker(selection: $selectedItem, matching: .images) {
Label("Select a photo", systemImage: "fork.knife")
}
.onChange(of: selectedItem, loadPhoto)
.listRowBackground(Color.clear)
.padding()
}
.listRowBackground(Color.clear)
.padding()
Spacer()
HStack {
Text("Notes")
.padding()
.font(.headline)
Spacer()
}
TextEditor(text: $review.reviewNotes, selection: $selection)
.background(Color.white.opacity(0.40))
}
.scrollDismissesKeyboard(.immediately)
}
.scrollContentBackground(.hidden)
.toolbar {
ToolbarItem(placement: .cancellationAction) {
Button("Dismiss") {
isPresentingNewMealView = false
}
}
ToolbarItem(placement: .confirmationAction) {
Button("Add") {
let newReview = review
modelContext.insert(newReview)
isPresentingNewMealView = false
}
}
}
}
}
func loadPhoto() {
Task { @MainActor in
review.foodImage = try await selectedItem?.loadTransferable(type: Data.self)
}
}
}
地址视图
import SwiftUI
import MapKit
import SwiftData
struct AddressView: View {
@State private var locationService = LocationService(completer: .init())
@State private var search: String = ""
@Binding var isPresentingLocationView: Bool
@Bindable var review: Review
var body: some View {
NavigationStack {
ZStack {
LinearGradient(gradient: Gradient(colors: [Color(red: 0.9725490196078431, green: 0.9607843137254902, blue: 0.8627450980392157, opacity: 1), Color(red: 0.9137254901960784, green: 0.9254901960784314, blue: 0.8509803921568627, opacity: 1), Color(red: 0.9882352941176471, green: 0.7529411764705882, blue: 0.13333333333333333, opacity: 1), Color(red: 0.9450980392156862, green: 0.47058823529411764, blue: 0.08627450980392157, opacity: 1)]), startPoint: .top, endPoint: .bottom).ignoresSafeArea()
.navigationTitle("Add Location")
VStack {
HStack {
Image(systemName: "magnifyingglass")
TextField("Search for a restaurant", text: $search)
.autocorrectionDisabled()
}
Spacer()
List {
ForEach(locationService.completions) { completion in
Button(action: {didTapOnCompletion(completion)}) {
VStack(alignment: .leading, spacing: 4) {
Text(completion.title)
.font(.headline)
.fontDesign(.rounded)
Text(completion.subTitle)
}
}
.listRowBackground(Color.clear)
}
}
.listStyle(.plain)
.scrollContentBackground(.hidden)
}
.onChange(of: search) {
locationService.update(queryFragment: search)
}
.padding()
.presentationBackground(.regularMaterial)
.presentationBackgroundInteraction(.enabled(upThrough: .large))
}
}
}
private func didTapOnCompletion(_ completion: SearchCompletions) {
isPresentingLocationView = false
review.restaurantName = completion.title
review.location = completion.subTitle
print("this is the name \(review.restaurantName) and this is the location \(review.location)")
}
}
我不明白发生了什么。这里还有一个小 gif。
