SwiftUI：如何使用动态生成的按钮将参数从一个视图传递到下一个视图？
SwiftUI: How to pass an argument from one view to the next with dynamically generated buttons?
问题：
- 当从 Landing.swift 传递输入参数时，我无法强制打开我的 alpha、beta 或 gamma 按钮。
- 我不明白为什么当
onAppear 在堆栈中触发时，输出变为：
gamma is the title
beta is the title
alpha is the title
gamma is the title
beta is the title
alpha is the title
困惑 -> 当 ForEach 循环内部只有 3 个元素时，为什么输出 2x？
背景：
我正在尝试将参数从一个视图 (Landing.swift) 传递到另一个视图 (ContentView.swift)，然后根据该参数强制正确的按钮（在 ContentView 中）触发 ON 状态，以便它被选中。我在 ButtonOnOff.swift 中显示了下面的逻辑，可以跟踪选择的内容和未选择的内容。
例如，ContentView 中有 3 个按钮（alpha、beta 和 gamma），并且根据从 Landing 中选择的输入按钮选择，相应的 alpha、beta 或 gamma 按钮（在 ContentView 中）应该打开。
我正在 ContentView 中动态生成这 3 个按钮，并希望将来可以灵活地扩展到 10 个或更多。因此，为什么我在 ContentView 中使用 ForEach。我需要一些帮助，请理解我是否错误地使用了 EnvironmentObject/ObservedObject 或其他东西。
维护 ON/OFF 逻辑与代码一起正常工作。也就是说，如果您手动按下 alpha，它会打开，但其他两个会关闭，依此类推。
提前感谢您的帮助！ :)
Testing.swift
import SwiftUI
@main
struct Testing: App {
@StateObject var buttonsEnvironmentObject = ButtonOnOff()
var body: some Scene {
WindowGroup {
Landing().environmentObject(buttonsEnvironmentObject)
}
}
}
Landing.swift
import SwiftUI
struct Landing: View {
@State private var tag:String? = nil
var body: some View {
NavigationView {
ZStack{
HStack{
NavigationLink(destination: ContentView(landingChoice:tag ?? ""), tag: tag ?? "", selection: $tag) {
EmptyView()
}
Button(action: {
self.tag = "alpha"
}) {
HStack {
Text("alpha")
}
}
Button(action: {
self.tag = "beta"
}) {
HStack {
Text("beta")
}
}
Button(action: {
self.tag = "gamma"
}) {
HStack {
Text("gamma")
}
}
}
.navigationBarHidden(true)
}
.navigationViewStyle(StackNavigationViewStyle())
}
}
}
ContentView.swift
import SwiftUI
struct ContentView: View {
var btnName:String
@EnvironmentObject var buttonEnvObj:ButtonOnOff
init(landingChoice:String){
self.btnName = landingChoice
print("\(self.btnName) is the input string")
}
var body: some View {
VStack{
Form{
Section{
ScrollView(.horizontal, showsIndicators: false) {
HStack(spacing:10) {
ForEach(0..<buttonEnvObj.buttonNames.count) { index in
BubbleButton(label: "\(buttonEnvObj.buttonNames[index])")
.padding(EdgeInsets(top: 5, leading: 5, bottom: 5, trailing: 0))
.onAppear {
print("\(buttonEnvObj.buttonNames[index]) is the title")
}
}
}
}.frame(height: 50)
}
}
}
}
}
struct BubbleButton: View{
@EnvironmentObject var buttonBrandButtons:ButtonOnOff
var label: String
var body: some View{
HStack{
Button(action: {
print("Button action")
buttonBrandButtons.changeState(buttonName: self.label)
}) {
ZStack {
VStack{
HStack {
Spacer()
Text(label)
.font(.system(size: 12,weight:.regular, design: .default))
.foregroundColor(buttonBrandButtons.buttonBrand[self.label]! ? Color.white : Color.gray)
Spacer()
}
}
.frame(height:30)
.fixedSize()
}
}
.background(buttonBrandButtons.buttonBrand[self.label]! ? Color.blue : .clear)
.cornerRadius(15)
.overlay(buttonBrandButtons.buttonBrand[self.label]! ?
RoundedRectangle(cornerRadius: 15).stroke(Color.blue,lineWidth:1) : RoundedRectangle(cornerRadius: 15).stroke(Color.gray,lineWidth:1))
.animation(.linear, value: 0.15)
}
}
}
ButtonOnOff.swift
import Foundation
class ButtonOnOff:ObservableObject{
var buttonNames = ["alpha","beta","gamma"]
@Published var buttonBrand:[String:Bool] = [
"alpha":false,
"beta":false,
"gamma":false
]
func changeState(buttonName:String) -> Void {
for (key,_) in buttonBrand{
if key == buttonName && buttonBrand[buttonName] == true{
buttonBrand[buttonName] = false
} else{
buttonBrand[key] = (key == buttonName) ? true : false
}
}
print(buttonBrand)
}
}
如需简短回答，只需添加
.onAppear(){
buttonEnvObj.changeState(buttonName: self.btnName)
}
到 ContentView 将突出显示所选的按钮。
至于一个可以随意扩展的方案。我会建议一切都采用单一事实来源并进行一些简化。
struct Landing: View {
@EnvironmentObject var buttonEnvObj:ButtonOnOff
@State private var tag:String? = nil
var body: some View {
NavigationView {
ZStack{
HStack{
NavigationLink(destination: ContentView(), tag: tag ?? "", selection: $tag) {
EmptyView()
}
//Put your buttons here
HStack{
//Use the keys of the dictionary to create the buttons
ForEach(buttonEnvObj.buttonBrand.keys.sorted(by: <), id: \.self){ key in
//Have the button set the value when pressed
Button(action: {
self.tag = key
buttonEnvObj.changeState(buttonName: key)
}) {
Text(key)
}
}
}
}
.navigationBarHidden(true)
}
.navigationViewStyle(StackNavigationViewStyle())
}
}
}
struct ContentView: View {
@EnvironmentObject var buttonEnvObj:ButtonOnOff
var body: some View {
VStack{
Form{
Section{
ScrollView(.horizontal, showsIndicators: false) {
HStack(spacing:10) {
//Change this to use the dictionary
ForEach(buttonEnvObj.buttonBrand.sorted(by: {[=11=].key < .key }), id:\.key) { key, value in
BubbleButton(key: key, value: value)
.padding(EdgeInsets(top: 5, leading: 5, bottom: 5, trailing: 0))
.onAppear {
print("\(value) is the title")
}
}
}
}.frame(height: 50)
}
}
}
}
}
struct BubbleButton: View{
@EnvironmentObject var buttonBrandButtons:ButtonOnOff
var key: String
var value: Bool
var body: some View{
HStack{
Button(action: {
print("Button action")
buttonBrandButtons.changeState(buttonName: key)
}) {
ZStack {
VStack{
HStack {
Spacer()
Text(key)
.font(.system(size: 12,weight:.regular, design: .default))
.foregroundColor(value ? Color.white : Color.gray)
Spacer()
}
}
.frame(height:30)
.fixedSize()
}
}
.background(value ? Color.blue : .clear)
.cornerRadius(15)
.overlay(value ?
RoundedRectangle(cornerRadius: 15).stroke(Color.blue,lineWidth:1) : RoundedRectangle(cornerRadius: 15).stroke(Color.gray,lineWidth:1))
.animation(.linear, value: 0.15)
}
}
}
class ButtonOnOff:ObservableObject{
//Get rid of this so you can keep the single source
//var buttonNames = ["alpha","beta","gamma"]
//When you want to add buttons just add them here it will all adjust
@Published var buttonBrand:[String:Bool] = [
"alpha":false,
"beta":false,
"gamma":false
]
func changeState(buttonName:String) -> Void {
for (key,_) in buttonBrand{
if key == buttonName && buttonBrand[buttonName] == true{
buttonBrand[buttonName] = false
} else{
buttonBrand[key] = (key == buttonName) ? true : false
}
}
print(buttonBrand)
}
}
问题：
- 当从 Landing.swift 传递输入参数时，我无法强制打开我的 alpha、beta 或 gamma 按钮。
- 我不明白为什么当
onAppear在堆栈中触发时，输出变为：
gamma is the title
beta is the title
alpha is the title
gamma is the title
beta is the title
alpha is the title
困惑 -> 当 ForEach 循环内部只有 3 个元素时，为什么输出 2x？
背景： 我正在尝试将参数从一个视图 (Landing.swift) 传递到另一个视图 (ContentView.swift)，然后根据该参数强制正确的按钮（在 ContentView 中）触发 ON 状态，以便它被选中。我在 ButtonOnOff.swift 中显示了下面的逻辑，可以跟踪选择的内容和未选择的内容。
例如，ContentView 中有 3 个按钮（alpha、beta 和 gamma），并且根据从 Landing 中选择的输入按钮选择，相应的 alpha、beta 或 gamma 按钮（在 ContentView 中）应该打开。
我正在 ContentView 中动态生成这 3 个按钮，并希望将来可以灵活地扩展到 10 个或更多。因此，为什么我在 ContentView 中使用 ForEach。我需要一些帮助，请理解我是否错误地使用了 EnvironmentObject/ObservedObject 或其他东西。
维护 ON/OFF 逻辑与代码一起正常工作。也就是说，如果您手动按下 alpha，它会打开，但其他两个会关闭，依此类推。
提前感谢您的帮助！ :)
Testing.swift
import SwiftUI
@main
struct Testing: App {
@StateObject var buttonsEnvironmentObject = ButtonOnOff()
var body: some Scene {
WindowGroup {
Landing().environmentObject(buttonsEnvironmentObject)
}
}
}
Landing.swift
import SwiftUI
struct Landing: View {
@State private var tag:String? = nil
var body: some View {
NavigationView {
ZStack{
HStack{
NavigationLink(destination: ContentView(landingChoice:tag ?? ""), tag: tag ?? "", selection: $tag) {
EmptyView()
}
Button(action: {
self.tag = "alpha"
}) {
HStack {
Text("alpha")
}
}
Button(action: {
self.tag = "beta"
}) {
HStack {
Text("beta")
}
}
Button(action: {
self.tag = "gamma"
}) {
HStack {
Text("gamma")
}
}
}
.navigationBarHidden(true)
}
.navigationViewStyle(StackNavigationViewStyle())
}
}
}
ContentView.swift
import SwiftUI
struct ContentView: View {
var btnName:String
@EnvironmentObject var buttonEnvObj:ButtonOnOff
init(landingChoice:String){
self.btnName = landingChoice
print("\(self.btnName) is the input string")
}
var body: some View {
VStack{
Form{
Section{
ScrollView(.horizontal, showsIndicators: false) {
HStack(spacing:10) {
ForEach(0..<buttonEnvObj.buttonNames.count) { index in
BubbleButton(label: "\(buttonEnvObj.buttonNames[index])")
.padding(EdgeInsets(top: 5, leading: 5, bottom: 5, trailing: 0))
.onAppear {
print("\(buttonEnvObj.buttonNames[index]) is the title")
}
}
}
}.frame(height: 50)
}
}
}
}
}
struct BubbleButton: View{
@EnvironmentObject var buttonBrandButtons:ButtonOnOff
var label: String
var body: some View{
HStack{
Button(action: {
print("Button action")
buttonBrandButtons.changeState(buttonName: self.label)
}) {
ZStack {
VStack{
HStack {
Spacer()
Text(label)
.font(.system(size: 12,weight:.regular, design: .default))
.foregroundColor(buttonBrandButtons.buttonBrand[self.label]! ? Color.white : Color.gray)
Spacer()
}
}
.frame(height:30)
.fixedSize()
}
}
.background(buttonBrandButtons.buttonBrand[self.label]! ? Color.blue : .clear)
.cornerRadius(15)
.overlay(buttonBrandButtons.buttonBrand[self.label]! ?
RoundedRectangle(cornerRadius: 15).stroke(Color.blue,lineWidth:1) : RoundedRectangle(cornerRadius: 15).stroke(Color.gray,lineWidth:1))
.animation(.linear, value: 0.15)
}
}
}
ButtonOnOff.swift
import Foundation
class ButtonOnOff:ObservableObject{
var buttonNames = ["alpha","beta","gamma"]
@Published var buttonBrand:[String:Bool] = [
"alpha":false,
"beta":false,
"gamma":false
]
func changeState(buttonName:String) -> Void {
for (key,_) in buttonBrand{
if key == buttonName && buttonBrand[buttonName] == true{
buttonBrand[buttonName] = false
} else{
buttonBrand[key] = (key == buttonName) ? true : false
}
}
print(buttonBrand)
}
}
如需简短回答，只需添加
.onAppear(){
buttonEnvObj.changeState(buttonName: self.btnName)
}
到 ContentView 将突出显示所选的按钮。
至于一个可以随意扩展的方案。我会建议一切都采用单一事实来源并进行一些简化。
struct Landing: View {
@EnvironmentObject var buttonEnvObj:ButtonOnOff
@State private var tag:String? = nil
var body: some View {
NavigationView {
ZStack{
HStack{
NavigationLink(destination: ContentView(), tag: tag ?? "", selection: $tag) {
EmptyView()
}
//Put your buttons here
HStack{
//Use the keys of the dictionary to create the buttons
ForEach(buttonEnvObj.buttonBrand.keys.sorted(by: <), id: \.self){ key in
//Have the button set the value when pressed
Button(action: {
self.tag = key
buttonEnvObj.changeState(buttonName: key)
}) {
Text(key)
}
}
}
}
.navigationBarHidden(true)
}
.navigationViewStyle(StackNavigationViewStyle())
}
}
}
struct ContentView: View {
@EnvironmentObject var buttonEnvObj:ButtonOnOff
var body: some View {
VStack{
Form{
Section{
ScrollView(.horizontal, showsIndicators: false) {
HStack(spacing:10) {
//Change this to use the dictionary
ForEach(buttonEnvObj.buttonBrand.sorted(by: {[=11=].key < .key }), id:\.key) { key, value in
BubbleButton(key: key, value: value)
.padding(EdgeInsets(top: 5, leading: 5, bottom: 5, trailing: 0))
.onAppear {
print("\(value) is the title")
}
}
}
}.frame(height: 50)
}
}
}
}
}
struct BubbleButton: View{
@EnvironmentObject var buttonBrandButtons:ButtonOnOff
var key: String
var value: Bool
var body: some View{
HStack{
Button(action: {
print("Button action")
buttonBrandButtons.changeState(buttonName: key)
}) {
ZStack {
VStack{
HStack {
Spacer()
Text(key)
.font(.system(size: 12,weight:.regular, design: .default))
.foregroundColor(value ? Color.white : Color.gray)
Spacer()
}
}
.frame(height:30)
.fixedSize()
}
}
.background(value ? Color.blue : .clear)
.cornerRadius(15)
.overlay(value ?
RoundedRectangle(cornerRadius: 15).stroke(Color.blue,lineWidth:1) : RoundedRectangle(cornerRadius: 15).stroke(Color.gray,lineWidth:1))
.animation(.linear, value: 0.15)
}
}
}
class ButtonOnOff:ObservableObject{
//Get rid of this so you can keep the single source
//var buttonNames = ["alpha","beta","gamma"]
//When you want to add buttons just add them here it will all adjust
@Published var buttonBrand:[String:Bool] = [
"alpha":false,
"beta":false,
"gamma":false
]
func changeState(buttonName:String) -> Void {
for (key,_) in buttonBrand{
if key == buttonName && buttonBrand[buttonName] == true{
buttonBrand[buttonName] = false
} else{
buttonBrand[key] = (key == buttonName) ? true : false
}
}
print(buttonBrand)
}
}