SwiftUI更新父级NavigationView的数据 [英] SwiftUI update data for parent NavigationView
问题描述
如何更新存在于NavigationView详细信息中的TextField中的数据?我希望在父视图的列表中更新数据.这是我的代码:
how can I update data in TextField that lives in the detail of a NavigationView? I want the data to be updated in the List of the parent View. Here is my code:
class Address: ObservableObject, Identifiable {
let id = UUID()
@Published var name: String
@Published var age: String
init(name: String, age: String) {
self.name = name
self.age = age
}
}
class AddressBook: ObservableObject {
@Published var addresses: [Address]
init(addresses: [Address]) {
self.addresses = addresses
}
}
struct TestData {
static let addressbook = AddressBook(addresses: [
Address(name: "Person1", age: "39"),
Address(name: "Person2", age: "22")
])
}
struct ContentView: View {
@ObservedObject var addressbook = TestData.addressbook
var body: some View {
NavigationView {
List (addressbook.addresses) {address in
NavigationLink(destination: AddressDetail(address: address)) {
Text(address.name)
}
}
.navigationBarTitle("Addressbook")
}
}
}
struct AddressDetail: View {
@ObservedObject var address: Address
var body: some View {
Form {
TextField("name", text: $address.name)
TextField("age", text: $address.age)
}
}
}
此代码不起作用:如果我转到AddressDetail-View,更改TextField值,然后返回,则更改不会在List-View中更新.
This code doesn't work: If I go to the AddressDetail-View, change the TextField values and then go back, the changes don't update in the List-View.
Nico
推荐答案
问题是 Address
是一个类,因此,如果其已发布的属性更改了 addresses
中的引用,不会更改,但是 ContentView
视图将 addressbook
视为地址的容器.
The problem is that Address
is a class, so if its published properties changed the reference in addresses
is not changed, but ContentView
view observes addressbook
as a container of addresses.
这里是可能方法的演示(经过测试并在Xcode 12b/iOS 14上运行,也可以在11.4/iOS 13.4上使用)
Here is demo of possible approach (tested & works with Xcode 12b / iOS 14, also on 11.4 / iOS 13.4)
List (addressbook.addresses) {address in
NavigationLink(destination: AddressDetail(address: address)) {
Text(address.name)
.onReceive(address.objectWillChange) { _ in
self.addressbook.objectWillChange.send()
}
}
}
备用:(基于 Binding
(需要进行更多更改,因此,对我而言,较不受欢迎,但值得一提
Alternate: based on Binding
(requires much more changes, so, as for me, less preferable, but worth mention
struct Address: Identifiable, Hashable {
let id = UUID()
var name: String
var age: String
init(name: String, age: String) {
self.name = name
self.age = age
}
}
class AddressBook: ObservableObject {
@Published var addresses: [Address]
init(addresses: [Address]) {
self.addresses = addresses
}
}
struct TestData {
static let addressbook = AddressBook(addresses: [
Address(name: "Person1", age: "39"),
Address(name: "Person2", age: "22")
])
}
struct ContentView: View {
@ObservedObject var addressbook = TestData.addressbook
var body: some View {
NavigationView {
List (Array(addressbook.addresses.enumerated()), id: \.element) { i, address in
NavigationLink(destination: AddressDetail(address: self.$addressbook.addresses[i])) {
Text(address.name)
}
}
.navigationBarTitle("Addressbook")
}
}
}
struct AddressDetail: View {
@Binding var address: Address
@State private var name: String
@State private var age: String
init(address: Binding<Address>) {
_address = address
_name = State(initialValue: _address.wrappedValue.name)
_age = State(initialValue: _address.wrappedValue.age)
}
var body: some View {
Form {
TextField("name", text: $name)
TextField("age", text: $age)
}
.onDisappear {
self.address.name = self.name
self.address.age = self.age
}
}
}
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