[英]NavigationView and NavigationLink on button click in SwiftUI?
我正在嘗試從登錄視圖推送到詳細信息視圖,但無法成功。即使是導航欄也沒有顯示在登錄視圖中。 如何在 SwiftUI 中點擊按鈕? 如何在單擊按鈕時使用 NavigationLink?
var body: some View {
NavigationView {
VStack(alignment: .leading) {
Text("Let's get you signed in.")
.bold()
.font(.system(size: 40))
.multilineTextAlignment(.leading)
.frame(width: 300, height: 100, alignment: .topLeading)
.padding(Edge.Set.bottom, 50)
Text("Email address:")
.font(.headline)
TextField("Email", text: $email)
.frame(height:44)
.accentColor(Color.white)
.background(Color(UIColor.darkGray))
.cornerRadius(4.0)
Text("Password:")
.font(.headline)
SecureField("Password", text: $password)
.frame(height:44)
.accentColor(Color.white)
.background(Color(UIColor.darkGray))
.cornerRadius(4.0)
Button(action: {
print("login tapped")
}) {
HStack {
Spacer()
Text("Login").foregroundColor(Color.white).bold()
Spacer()
}
}
.accentColor(Color.black)
.padding()
.background(Color(UIColor.darkGray))
.cornerRadius(4.0)
.padding(Edge.Set.vertical, 20)
}
.padding(.horizontal,30)
}
.navigationBarTitle(Text("Login"))
}
要解決您的問題,您需要使用NavigationLink
綁定和管理標簽,因此在您的視圖中創建一個狀態,如下所示,只需添加上面的正文。
@State var selection: Int? = nil
然后按如下方式更新您的按鈕代碼以添加NavigationLink
NavigationLink(destination: Text("Test"), tag: 1, selection: $selection) {
Button(action: {
print("login tapped")
self.selection = 1
}) {
HStack {
Spacer()
Text("Login").foregroundColor(Color.white).bold()
Spacer()
}
}
.accentColor(Color.black)
.padding()
.background(Color(UIColor.darkGray))
.cornerRadius(4.0)
.padding(Edge.Set.vertical, 20)
}
Meaning is, when selection and NavigationLink
tag value will match then navigation will be occurs.
我希望這能幫到您。
接受的答案使用正確的NavigationLink(destination:tag:selection:)
。
但是,對於只有一個NavigationLink
的簡單視圖,您可以使用更簡單的變體: NavigationLink(destination:isActive:)
用法 #1
NavigationLink
由標准Button
激活:
struct ContentView: View {
@State var isLinkActive = false
var body: some View {
NavigationView {
VStack(alignment: .leading) {
...
NavigationLink(destination: Text("OtherView"), isActive: $isLinkActive) {
Button(action: {
self.isLinkActive = true
}) {
Text("Login")
}
}
}
.navigationBarTitle(Text("Login"))
}
}
}
用法 #2
NavigationLink
由標准Button
隱藏和激活:
struct ContentView: View {
@State var isLinkActive = false
var body: some View {
NavigationView {
VStack(alignment: .leading) {
...
Button(action: {
self.isLinkActive = true
}) {
Text("Login")
}
}
.navigationBarTitle(Text("Login"))
.background(
NavigationLink(destination: Text("OtherView"), isActive: $isLinkActive) {
EmptyView()
}
.hidden()
)
}
}
}
用法 #3
NavigationLink
以編程方式隱藏和激活:
struct ContentView: View {
@State var isLinkActive = false
var body: some View {
NavigationView {
VStack(alignment: .leading) {
...
}
.navigationBarTitle(Text("Login"))
.background(
NavigationLink(destination: Text("OtherView"), isActive: $isLinkActive) {
EmptyView()
}
.hidden()
)
}
.onAppear {
self.isLinkActive = true
}
}
}
這是一個GitHub 存儲庫,它具有不同的 SwiftUI 擴展,使導航更容易。
另一種方法:
場景委托
if let windowScene = scene as? UIWindowScene {
let window = UIWindow(windowScene: windowScene)
window.rootViewController = UIHostingController(rootView: BaseView().environmentObject(ViewRouter()))
self.window = window
window.makeKeyAndVisible()
}
基礎視圖
import SwiftUI
struct BaseView : View {
@EnvironmentObject var viewRouter: ViewRouter
var body: some View {
VStack {
if viewRouter.currentPage == "view1" {
FirstView()
} else if viewRouter.currentPage == "view2" {
SecondView()
.transition(.scale)
}
}
}
}
#if DEBUG
struct MotherView_Previews : PreviewProvider {
static var previews: some View {
BaseView().environmentObject(ViewRouter())
}
}
#endif
視圖路由器
import Foundation
import Combine
import SwiftUI
class ViewRouter: ObservableObject {
let objectWillChange = PassthroughSubject<ViewRouter,Never>()
var currentPage: String = "view1" {
didSet {
withAnimation() {
objectWillChange.send(self)
}
}
}
}
第一視圖
import SwiftUI
struct FirstView : View {
@EnvironmentObject var viewRouter: ViewRouter
var body: some View {
VStack {
Button(action: {self.viewRouter.currentPage = "view2"}) {
NextButtonContent()
}
}
}
}
#if DEBUG
struct FirstView_Previews : PreviewProvider {
static var previews: some View {
FirstView().environmentObject(ViewRouter())
}
}
#endif
struct NextButtonContent : View {
var body: some View {
return Text("Next")
.foregroundColor(.white)
.frame(width: 200, height: 50)
.background(Color.blue)
.cornerRadius(15)
.padding(.top, 50)
}
}
第二視圖
import SwiftUI
struct SecondView : View {
@EnvironmentObject var viewRouter: ViewRouter
var body: some View {
VStack {
Spacer(minLength: 50.0)
Button(action: {self.viewRouter.currentPage = "view1"}) {
BackButtonContent()
}
}
}
}
#if DEBUG
struct SecondView_Previews : PreviewProvider {
static var previews: some View {
SecondView().environmentObject(ViewRouter())
}
}
#endif
struct BackButtonContent : View {
var body: some View {
return Text("Back")
.foregroundColor(.white)
.frame(width: 200, height: 50)
.background(Color.blue)
.cornerRadius(15)
.padding(.top, 50)
}
}
希望這可以幫助!
最簡單和最有效的解決方案是:
NavigationLink(destination:ScoresTableView()) {
Text("Scores")
}.navigationBarHidden(true)
.frame(width: 90, height: 45, alignment: .center)
.foregroundColor(.white)
.background(LinearGradient(gradient: Gradient(colors: [Color.red, Color.blue]), startPoint: .leading, endPoint: .trailing))
.cornerRadius(10)
.contentShape(Rectangle())
.padding(EdgeInsets(top: 16, leading: UIScreen.main.bounds.size.width - 110 , bottom: 16, trailing: 20))
ScoresTableView 是目標視圖。
我認為上面的答案很好,但更簡單的方法應該是:
NavigationLink {
TargetView()
} label: {
Text("Click to go")
}
在我看來, iOS 16+更簡潔的方法是使用 state bool 來呈現視圖。
struct ButtonNavigationView: View {
@State private var isShowingSecondView : Bool = false
var body: some View {
NavigationStack {
VStack{
Button(action:{isShowingSecondView = true} ){
Text("Show second view")
}
}.navigationDestination(isPresented: $isShowingSecondView) {
Text("SecondView")
}
}
}
}
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