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mattrighettimattrighetti
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Initial implementation and working example
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‎README.md‎

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## TextKit Editor
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This is a super simple code editor made with TextKit APIs with some dumb syntax highlighting logic.
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I have created this project to learn how `NSTextContainer`, `NSTextStorage`, `NSLayoutManager` and `UITextView` work and render text.
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The `UITextView` has then been wrapped in a `UIViewRepresentable` view and used in a SwiftUI application
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<p align="center">
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<img src="img/colored.png" height="450px">
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<img src="img/plain.png" height="450px">
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</p>

‎TextKitEditor.xcodeproj/project.pbxproj‎

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/* Begin PBXBuildFile section */
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C907279026063A8600CAFAA5 /* TextKitEditorApp.swift in Sources */ = {isa = PBXBuildFile; fileRef = C907278F26063A8600CAFAA5 /* TextKitEditorApp.swift */; };
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C907279226063A8600CAFAA5 /* ContentView.swift in Sources */ = {isa = PBXBuildFile; fileRef = C907279126063A8600CAFAA5 /* ContentView.swift */; };
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C907279226063A8600CAFAA5 /* EditorView.swift in Sources */ = {isa = PBXBuildFile; fileRef = C907279126063A8600CAFAA5 /* EditorView.swift */; };
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C907279426063A8700CAFAA5 /* Assets.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = C907279326063A8700CAFAA5 /* Assets.xcassets */; };
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C907279726063A8700CAFAA5 /* Preview Assets.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = C907279626063A8700CAFAA5 /* Preview Assets.xcassets */; };
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C907279F26063A9600CAFAA5 /* TextContainer.swift in Sources */ = {isa = PBXBuildFile; fileRef = C907279E26063A9600CAFAA5 /* TextContainer.swift */; };
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C90727A12606677200CAFAA5 /* CodeString.swift in Sources */ = {isa = PBXBuildFile; fileRef = C90727A02606677200CAFAA5 /* CodeString.swift */; };
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C90727A32606679300CAFAA5 /* TextStorage.swift in Sources */ = {isa = PBXBuildFile; fileRef = C90727A22606679300CAFAA5 /* TextStorage.swift */; };
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C90727A5260667B600CAFAA5 /* LayoutManager.swift in Sources */ = {isa = PBXBuildFile; fileRef = C90727A4260667B600CAFAA5 /* LayoutManager.swift */; };
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C90727A826066FB300CAFAA5 /* CodeTypeText.swift in Sources */ = {isa = PBXBuildFile; fileRef = C90727A726066FB300CAFAA5 /* CodeTypeText.swift */; };
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C90727AB2606A8F100CAFAA5 /* sample.txt in Resources */ = {isa = PBXBuildFile; fileRef = C90727AA2606A8F100CAFAA5 /* sample.txt */; };
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/* End PBXBuildFile section */
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/* Begin PBXFileReference section */
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C907278C26063A8600CAFAA5 /* TextKitEditor.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = TextKitEditor.app; sourceTree = BUILT_PRODUCTS_DIR; };
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C907278F26063A8600CAFAA5 /* TextKitEditorApp.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TextKitEditorApp.swift; sourceTree = "<group>"; };
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C907279126063A8600CAFAA5 /* ContentView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ContentView.swift; sourceTree = "<group>"; };
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C907279126063A8600CAFAA5 /* EditorView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = EditorView.swift; sourceTree = "<group>"; };
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C907279326063A8700CAFAA5 /* Assets.xcassets */ = {isa = PBXFileReference; lastKnownFileType = folder.assetcatalog; path = Assets.xcassets; sourceTree = "<group>"; };
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C907279626063A8700CAFAA5 /* Preview Assets.xcassets */ = {isa = PBXFileReference; lastKnownFileType = folder.assetcatalog; path = "Preview Assets.xcassets"; sourceTree = "<group>"; };
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C907279826063A8700CAFAA5 /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
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C907279E26063A9600CAFAA5 /* TextContainer.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TextContainer.swift; sourceTree = "<group>"; };
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C90727A02606677200CAFAA5 /* CodeString.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CodeString.swift; sourceTree = "<group>"; };
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C90727A22606679300CAFAA5 /* TextStorage.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TextStorage.swift; sourceTree = "<group>"; };
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C90727A4260667B600CAFAA5 /* LayoutManager.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LayoutManager.swift; sourceTree = "<group>"; };
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C90727A726066FB300CAFAA5 /* CodeTypeText.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CodeTypeText.swift; sourceTree = "<group>"; };
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C90727AA2606A8F100CAFAA5 /* sample.txt */ = {isa = PBXFileReference; lastKnownFileType = text; path = sample.txt; sourceTree = "<group>"; };
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/* End PBXFileReference section */
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/* Begin PBXFrameworksBuildPhase section */
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C907278E26063A8600CAFAA5 /* TextKitEditor */ = {
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isa = PBXGroup;
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children = (
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C90727A92606A8C600CAFAA5 /* Supporting Files */,
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C907278F26063A8600CAFAA5 /* TextKitEditorApp.swift */,
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C907279126063A8600CAFAA5 /* ContentView.swift */,
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C907279326063A8700CAFAA5 /* Assets.xcassets */,
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C907279826063A8700CAFAA5 /* Info.plist */,
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C907279526063A8700CAFAA5 /* Preview Content */,
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C90727A62606680E00CAFAA5 /* Elements */,
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);
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path = TextKitEditor;
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sourceTree = "<group>";
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path = "Preview Content";
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sourceTree = "<group>";
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};
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C90727A62606680E00CAFAA5 /* Elements */ = {
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isa = PBXGroup;
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children = (
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C907279126063A8600CAFAA5 /* EditorView.swift */,
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C907279E26063A9600CAFAA5 /* TextContainer.swift */,
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C90727A02606677200CAFAA5 /* CodeString.swift */,
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C90727A22606679300CAFAA5 /* TextStorage.swift */,
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C90727A4260667B600CAFAA5 /* LayoutManager.swift */,
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C90727A726066FB300CAFAA5 /* CodeTypeText.swift */,
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);
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path = Elements;
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sourceTree = "<group>";
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};
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C90727A92606A8C600CAFAA5 /* Supporting Files */ = {
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isa = PBXGroup;
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children = (
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C90727AA2606A8F100CAFAA5 /* sample.txt */,
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);
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path = "Supporting Files";
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sourceTree = "<group>";
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};
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/* End PBXGroup section */
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/* Begin PBXNativeTarget section */
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buildActionMask = 2147483647;
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files = (
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C907279726063A8700CAFAA5 /* Preview Assets.xcassets in Resources */,
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C90727AB2606A8F100CAFAA5 /* sample.txt in Resources */,
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C907279426063A8700CAFAA5 /* Assets.xcassets in Resources */,
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);
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runOnlyForDeploymentPostprocessing = 0;
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isa = PBXSourcesBuildPhase;
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buildActionMask = 2147483647;
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files = (
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C907279226063A8600CAFAA5 /* ContentView.swift in Sources */,
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C90727A32606679300CAFAA5 /* TextStorage.swift in Sources */,
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C90727A12606677200CAFAA5 /* CodeString.swift in Sources */,
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C907279226063A8600CAFAA5 /* EditorView.swift in Sources */,
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C907279026063A8600CAFAA5 /* TextKitEditorApp.swift in Sources */,
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C90727A5260667B600CAFAA5 /* LayoutManager.swift in Sources */,
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C907279F26063A9600CAFAA5 /* TextContainer.swift in Sources */,
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C90727A826066FB300CAFAA5 /* CodeTypeText.swift in Sources */,
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);
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runOnlyForDeploymentPostprocessing = 0;
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};

‎TextKitEditor/ContentView.swift‎

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‎TextKitEditor/Elements/CodeString.swift‎

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//
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// TKECodeString.swift
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// TextKitEditor
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//
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// Created by Mattia Righetti on 20/03/21.
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//
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import Foundation
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import UIKit
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class CodeString: NSString {
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var imp: NSMutableString
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override init() {
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imp = NSMutableString()
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super.init()
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}
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required init?(coder: NSCoder) {
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fatalError("init(coder:) has not been implemented")
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}
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// MARK: - String Accessors
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override var length: Int {
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imp.length
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}
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override func character(at index: Int) -> unichar {
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imp.character(at: index)
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}
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override func getCharacters(_ buffer: UnsafeMutablePointer<unichar>, range: NSRange) {
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imp.getCharacters(buffer, range: range)
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}
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func replaceCharacters(in range: NSRange, with aString: String) {
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imp.replaceCharacters(in: range, with: aString)
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}
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// MARK: - Code Intelligence
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func enumerateCode(in range: NSRange, usingBlock block: @escaping (_ range: NSRange, _ type: CodeType) -> Void) {
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assert(NSEqualRanges(range, paragraphRange(for: range)), "Invalid parameter not satisfying: NSEqualRanges(range, paragraphRange(for: range))")
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// Enumerate lines
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enumerateSubstrings(in: range, options: .byParagraphs, using: { [unowned self] paragraph, substringRange, enclosingRange, stop in
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// detect comments
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if (paragraph!.trimmingCharacters(in: .whitespaces).hasPrefix("//")) {
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block(enclosingRange, .Comment)
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return
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}
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// detect comments
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if (paragraph!.hasPrefix("#")) {
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block(enclosingRange, .Comment)
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return
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}
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// Detect keywords
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enumerateSubstrings(in: enclosingRange, options: .byWords, using: { word, innerSubstringRange, innerEnclosingRange, stop in
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// Substring is a keyword
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if ["int", "const", "char", "return"].contains(word) {
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// Text before keyword is just text
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if innerEnclosingRange.location < innerSubstringRange.location {
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block(NSMakeRange(innerEnclosingRange.location, innerSubstringRange.location - innerEnclosingRange.location), .Text)
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}
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// Keyword is a keyword
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block(innerSubstringRange, .Keyword)
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// Text behind keyword is just text
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if NSMaxRange(innerEnclosingRange) > NSMaxRange(innerSubstringRange) {
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block(NSMakeRange(NSMaxRange(innerSubstringRange), NSMaxRange(innerEnclosingRange) - NSMaxRange(innerSubstringRange)), .Text)
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}
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} else {
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block(innerEnclosingRange, .Text)
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}
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})
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})
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}
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func paragraphNumberForParagraph(at index: Int) -> Int {
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// WARNING: extremely inefficient implementation, should better be cached
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var number = 1
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enumerateSubstrings(in: NSMakeRange(0, index), options: [.byParagraphs, .substringNotRequired], using: { substring, substringRange, enclosingRange, stop in
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number += 1
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})
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return number
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}
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}

‎TextKitEditor/Elements/CodeTypeText.swift‎

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//
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// TKECodeTypeText.swift
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// TextKitEditor
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//
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// Created by Mattia Righetti on 20/03/21.
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//
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import Foundation
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enum CodeType: Int {
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case Text
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case Comment
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case Pragma
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case Keyword
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}

‎TextKitEditor/Elements/EditorView.swift‎

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//
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// ContentView.swift
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// TextKitEditor
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//
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// Created by Mattia Righetti on 20/03/21.
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//
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import SwiftUI
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struct EditorView: UIViewRepresentable {
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let code: String
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func makeUIView(context: Context) -> UITextView {
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let codeString = CodeString()
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let textStorage = TextStorage()
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textStorage.content = codeString
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textStorage.font = UIFont(name: "Menlo", size: 13)!
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let layoutManager = LayoutManager()
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textStorage.addLayoutManager(layoutManager)
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layoutManager.lineHeight = 1
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layoutManager.showParagraphNumbers = true
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layoutManager.tabWidth = 4
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let textContainer = TextContainer()
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layoutManager.addTextContainer(textContainer)
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let view = UITextView(frame: CGRect(origin: .zero, size: .zero), textContainer: textContainer)
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view.translatesAutoresizingMaskIntoConstraints = false
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view.keyboardDismissMode = .interactive
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view.spellCheckingType = .no
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view.text = code
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return view
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}
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func updateUIView(_ uiView: UITextView, context: Context) {}
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}
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struct TKEView_Previews: PreviewProvider {
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static var previews: some View {
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let codeString = """
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//
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// ContentView.swift
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// TextKitEditor
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//
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// Created by Mattia Righetti on 20/03/21.
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//
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import SwiftUI
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struct TKEView: UIViewRepresentable {
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let code: String
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func makeUIView(context: Context) -> UITextView {
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let codeString = TKECodeString()
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let textStorage = TKETextStorage()
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textStorage.content = codeString
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textStorage.font = UIFont(name: "Menlo", size: 13)
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let layoutManager = TKELayoutManager()
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layoutManager.lineHeight = 1
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layoutManager.showParagraphNumbers = true
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layoutManager.tabWidth = 4
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textStorage.addLayoutManager(layoutManager)
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let textContainer = TKETextContainer()
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layoutManager.addTextContainer(textContainer)
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let view = UITextView(frame: CGRect(origin: .zero, size: .zero), textContainer: textContainer)
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view.translatesAutoresizingMaskIntoConstraints = false
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view.keyboardDismissMode = .interactive
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view.spellCheckingType = .no
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return view
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}
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func updateUIView(_ uiView: UITextView, context: Context) {}
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}
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"""
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EditorView(code: codeString)
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}
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}

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