[英]How to set textfield character limit SwiftUI?
我正在使用 SwiftUi 版本 2 进行应用程序开发。 我遇到了 SwiftUI 中可用的文本字段的问题。 我不想再使用 UITextField 了。 我想限制 TextField 中的字符数。 我搜索了很多,我找到了一些与此相关的答案,但这些答案不适用于 SwiftUI 版本 2。
class textBindingManager: ObservableObject{
let characterLimit: Int
@Published var phoneNumber = "" {
didSet {
if phoneNumber.count > characterLimit && oldValue.count <= characterLimit {
phoneNumber = oldValue
}
}
}
init(limit: Int = 10) {
characterLimit = limit
}
}
struct ContentView: View {
@ObservedObject var textBindingManager = TextBindingManager(limit: 5)
var body: some View {
TextField("Placeholder", text: $textBindingManager.phoneNumber)
}
}
无需在您发布的属性上使用 didSet。 您可以向 TextField 添加修饰符并将字符串值限制为其前缀限制为字符限制:
import SwiftUI
struct ContentView: View {
@ObservedObject var textBindingManager = TextBindingManager(limit: 5)
var body: some View {
TextField("Placeholder", text: $textBindingManager.phoneNumber)
.padding()
.onChange(of: textBindingManager.phoneNumber, perform: editingChanged)
}
func editingChanged(_ value: String) {
textBindingManager.phoneNumber = String(value.prefix(textBindingManager.characterLimit))
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
class TextBindingManager: ObservableObject {
let characterLimit: Int
@Published var phoneNumber = ""
init(limit: Int = 10){
characterLimit = limit
}
}
此解决方案将所有内容包装在一个新组件中。 您可以调整它以非常轻松地执行其他解析/模式检查。
struct ContentView : View {
@State private var myTextValue: String = ""
var body: some View {
LimitedTextField(value: $myTextValue, charLimit: 2)
}
}
struct LimitedTextField : View {
@State private var enteredString: String = ""
@Binding var underlyingString: String
let charLimit : Int
init(value: Binding<String>, charLimit: Int) {
_underlyingString = value
self.charLimit = charLimit
}
var body: some View {
HStack {
TextField("", text: $enteredString, onCommit: updateUnderlyingValue)
.onAppear(perform: { updateEnteredString(newUnderlyingString: underlyingString) })
.onChange(of: enteredString, perform: updateUndelyingString)
.onChange(of: underlyingString, perform: updateEnteredString)
}
}
func updateEnteredString(newUnderlyingString: String) {
enteredString = String(newUnderlyingString.prefix(charLimit))
}
func updateUndelyingString(newEnteredString: String) {
if newEnteredString.count > charLimit {
self.enteredString = String(newEnteredString.prefix(charLimit))
underlyingString = self.enteredString
}
}
func updateUnderlyingValue() {
underlyingString = enteredString
}
}
以下应该是最简单的。 它将字符数限制为 10。
struct ContentView: View {
@State var searchKey: String = ""
var body: some View {
TextField("Enter text", text: $searchKey)
.onChange(of: searchKey) { newValue in
if newValue.count > 10 {
self.searchKey = String(newValue.prefix(10))
}
}
}
}
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