如何在下面的 NSTextView 上正确实现 NSView 约束，以便它与 SwiftUI .frame() 交互？
目标
一个 NSTextView，它在换行后垂直扩展其框架以强制 SwiftUI 父视图再次呈现（即，扩展文本下方的背景面板 + 下推 VStack 中的其他内容）。父视图已经包含在一个 ScrollView 中。由于 SwiftUI TextEditor 丑陋且功能不足，我猜其他几个 MacOS 新手会想知道如何做同样的事情。
更新
@Asperi 指出了一个隐藏在另一个线程中的 UIKit 示例。我尝试为 AppKit 调整它，但是 async recalculateHeight 函数中有一些循环。明天我会在喝咖啡时多看看它。谢谢阿斯佩里。（无论你是谁，你都是 SwiftUI SO 爸爸。）
问题
下面的 NSTextView 实现编辑愉快，但不服从 SwiftUI 的垂直框架。在水平方向上一切都被遵守，但文本只是继续向下超过垂直高度限制。除非，当将焦点移开时，编辑器会裁剪多余的文本……直到再次开始编辑。
我试过的
作为模特的帖子太多了。下面是一些。我认为我的不足是误解了如何设置约束，如何使用 NSTextView 对象，也许是想太多了。
- 我尝试在下面的代码中一起实现 NSTextContainer、NSLayoutManager 和 NSTextStorage 堆栈，但没有任何进展。
- 我玩过 GeometryReader 输入，没有骰子。
- 我在 textdidChange() 上打印了 LayoutManager 和 TextContainer 变量，但没有看到新行的尺寸变化。还尝试监听 .boundsDidChangeNotification / .frameDidChangeNotification。
- GitHub：未命名的 MacEditorTextView.swift <- 删除了它的 ScrollView，但这样做后无法立即获得文本约束
- SO：SwiftUI 中的多行可编辑文本字段<- 帮助我理解了如何换行，删除了 ScrollView
- SO：使用 layoutManager 的计算<- 我的实现不起作用
- Reddit：在 SwiftUI 中包装 NSTextView <- 提示似乎很到位，但缺乏可遵循的 AppKit 知识
- SO：使用intrinsicContentSize自动增长高度<-我的实现不起作用
- SO：更改 ScrollView <- 不知道如何推断
- SO：关于设置 NSTextView 的 Cocoa 教程
- 苹果 NSTextContainer 类
- Apple 跟踪文本视图的大小
内容视图.swift
import SwiftUI
import Combine
struct ContentView: View {
@State var text = NSAttributedString(string: "Testing.... testing...")
let nsFont: NSFont = .systemFont(ofSize: 20)
var body: some View {
// ScrollView would go here
VStack(alignment: .center) {
GeometryReader { geometry in
NSTextEditor(text: $text.didSet { text in react(to: text) },
nsFont: nsFont,
geometry: geometry)
.frame(width: 500, // Wraps to width
height: 300) // Disregards this during editing
.background(background)
}
Text("Editing text above should push this down.")
}
}
var background: some View {
...
}
// Seeing how updates come back; I prefer setting them on textDidEndEditing to work with a database
func react(to text: NSAttributedString) {
print(#file, #line, #function, text)
}
}
// Listening device into @State
extension Binding {
func didSet(_ then: @escaping (Value) ->Void) -> Binding {
return Binding(
get: {
return self.wrappedValue
},
set: {
then($0)
self.wrappedValue = $0
}
)
}
}
NSTextEditor.swift
import SwiftUI
struct NSTextEditor: View, NSViewRepresentable {
typealias Coordinator = NSTextEditorCoordinator
typealias NSViewType = NSTextView
@Binding var text: NSAttributedString
let nsFont: NSFont
var geometry: GeometryProxy
func makeNSView(context: NSViewRepresentableContext<NSTextEditor>) -> NSTextEditor.NSViewType {
return context.coordinator.textView
}
func updateNSView(_ nsView: NSTextView, context: NSViewRepresentableContext<NSTextEditor>) { }
func makeCoordinator() -> NSTextEditorCoordinator {
let coordinator = NSTextEditorCoordinator(binding: $text,
nsFont: nsFont,
proxy: geometry)
return coordinator
}
}
class NSTextEditorCoordinator : NSObject, NSTextViewDelegate {
let textView: NSTextView
var font: NSFont
var geometry: GeometryProxy
@Binding var text: NSAttributedString
init(binding: Binding<NSAttributedString>,
nsFont: NSFont,
proxy: GeometryProxy) {
_text = binding
font = nsFont
geometry = proxy
textView = NSTextView(frame: .zero)
textView.autoresizingMask = [.height, .width]
textView.textColor = NSColor.textColor
textView.drawsBackground = false
textView.allowsUndo = true
textView.isAutomaticLinkDetectionEnabled = true
textView.displaysLinkToolTips = true
textView.isAutomaticDataDetectionEnabled = true
textView.isAutomaticTextReplacementEnabled = true
textView.isAutomaticDashSubstitutionEnabled = true
textView.isAutomaticSpellingCorrectionEnabled = true
textView.isAutomaticQuoteSubstitutionEnabled = true
textView.isAutomaticTextCompletionEnabled = true
textView.isContinuousSpellCheckingEnabled = true
textView.usesAdaptiveColorMappingForDarkAppearance = true
// textView.importsGraphics = true // 100% size, layoutManger scale didn't fix
// textView.allowsImageEditing = true // NSFileWrapper error
// textView.isIncrementalSearchingEnabled = true
// textView.usesFindBar = true
// textView.isSelectable = true
// textView.usesInspectorBar = true
// Context Menu show styles crashes
super.init()
textView.textStorage?.setAttributedString($text.wrappedValue)
textView.delegate = self
}
// Calls on every character stroke
func textDidChange(_ notification: Notification) {
switch notification.name {
case NSText.boundsDidChangeNotification:
print("bounds did change")
case NSText.frameDidChangeNotification:
print("frame did change")
case NSTextView.frameDidChangeNotification:
print("FRAME DID CHANGE")
case NSTextView.boundsDidChangeNotification:
print("BOUNDS DID CHANGE")
default:
return
}
// guard notification.name == NSText.didChangeNotification,
// let update = (notification.object as? NSTextView)?.textStorage else { return }
// text = update
}
// Calls only after focus change
func textDidEndEditing(_ notification: Notification) {
guard notification.name == NSText.didEndEditingNotification,
let update = (notification.object as? NSTextView)?.textStorage else { return }
text = update
}
}
来自 UIKit 线程的快速 Asperi 的回答
碰撞
*** Assertion failure in -[NSCGSWindow setSize:], NSCGSWindow.m:1458
[General] Invalid parameter not satisfying:
size.width >= 0.0
&& size.width < (CGFloat)INT_MAX - (CGFloat)INT_MIN
&& size.height >= 0.0
&& size.height < (CGFloat)INT_MAX - (CGFloat)INT_MIN
import SwiftUI
struct AsperiMultiLineTextField: View {
private var placeholder: String
private var onCommit: (() -> Void)?
@Binding private var text: NSAttributedString
private var internalText: Binding<NSAttributedString> {
Binding<NSAttributedString>(get: { self.text } ) {
self.text = $0
self.showingPlaceholder = $0.string.isEmpty
}
}
@State private var dynamicHeight: CGFloat = 100
@State private var showingPlaceholder = false
init (_ placeholder: String = "", text: Binding<NSAttributedString>, onCommit: (() -> Void)? = nil) {
self.placeholder = placeholder
self.onCommit = onCommit
self._text = text
self._showingPlaceholder = State<Bool>(initialValue: self.text.string.isEmpty)
}
var body: some View {
NSTextViewWrapper(text: self.internalText, calculatedHeight: $dynamicHeight, onDone: onCommit)
.frame(minHeight: dynamicHeight, maxHeight: dynamicHeight)
.background(placeholderView, alignment: .topLeading)
}
@ViewBuilder
var placeholderView: some View {
if showingPlaceholder {
Text(placeholder).foregroundColor(.gray)
.padding(.leading, 4)
.padding(.top, 8)
}
}
}
fileprivate struct NSTextViewWrapper: NSViewRepresentable {
typealias NSViewType = NSTextView
@Binding var text: NSAttributedString
@Binding var calculatedHeight: CGFloat
var onDone: (() -> Void)?
func makeNSView(context: NSViewRepresentableContext<NSTextViewWrapper>) -> NSTextView {
let textField = NSTextView()
textField.delegate = context.coordinator
textField.isEditable = true
textField.font = NSFont.preferredFont(forTextStyle: .body)
textField.isSelectable = true
textField.drawsBackground = false
textField.allowsUndo = true
/// Disabled these lines as not available/neeed/appropriate for AppKit
// textField.isUserInteractionEnabled = true
// textField.isScrollEnabled = false
// if nil != onDone {
// textField.returnKeyType = .done
// }
textField.setContentCompressionResistancePriority(.defaultLow, for: .horizontal)
return textField
}
func makeCoordinator() -> Coordinator {
return Coordinator(text: $text, height: $calculatedHeight, onDone: onDone)
}
func updateNSView(_ NSView: NSTextView, context: NSViewRepresentableContext<NSTextViewWrapper>) {
NSTextViewWrapper.recalculateHeight(view: NSView, result: $calculatedHeight)
}
fileprivate static func recalculateHeight(view: NSView, result: Binding<CGFloat>) {
/// UIView.sizeThatFits is not available in AppKit. Tried substituting below, but there's a loop that crashes.
// let newSize = view.sizeThatFits(CGSize(width: view.frame.size.width, height: CGFloat.greatestFiniteMagnitude))
// tried reportedSize = view.frame, view.intrinsicContentSize
let reportedSize = view.fittingSize
let newSize = CGSize(width: reportedSize.width, height: CGFloat.greatestFiniteMagnitude)
if result.wrappedValue != newSize.height {
DispatchQueue.main.async {
result.wrappedValue = newSize.height // !! must be called asynchronously
}
}
}
final class Coordinator: NSObject, NSTextViewDelegate {
var text: Binding<NSAttributedString>
var calculatedHeight: Binding<CGFloat>
var onDone: (() -> Void)?
init(text: Binding<NSAttributedString>, height: Binding<CGFloat>, onDone: (() -> Void)? = nil) {
self.text = text
self.calculatedHeight = height
self.onDone = onDone
}
func textDidChange(_ notification: Notification) {
guard notification.name == NSText.didChangeNotification,
let textView = (notification.object as? NSTextView),
let latestText = textView.textStorage else { return }
text.wrappedValue = latestText
NSTextViewWrapper.recalculateHeight(view: textView, result: calculatedHeight)
}
func textView(_ textView: NSTextView, shouldChangeTextIn: NSRange, replacementString: String?) -> Bool {
if let onDone = self.onDone, replacementString == "\n" {
textView.resignFirstResponder()
onDone()
return false
}
return true
}
}
}