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import UIKit |
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import PlaygroundSupport |
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extension String { |
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subscript(range: NSRange) -> String? { |
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guard range.location + range.length <= self.characters.count else { |
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return nil |
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} |
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let r = index(startIndex, offsetBy: range.location)..<index(startIndex, offsetBy: range.location + range.length) |
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return self[r] |
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} |
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subscript(range: CountableRange<Int>) -> String? { |
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guard range.endIndex <= self.characters.count else { |
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return nil |
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} |
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let r = index(startIndex, offsetBy: range.startIndex)..<index(startIndex, offsetBy: range.endIndex) |
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return self[r] |
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} |
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} |
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class Tagger: NSObject, UITextFieldDelegate { |
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var tagStart: Int? = nil |
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var tagRange: CountableRange<Int>? = nil |
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func textField(_ textField: UITextField, |
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shouldChangeCharactersIn range: NSRange, |
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replacementString string: String) -> Bool { |
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if textField.text?.characters.count == 1 && range.length == 1 { |
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tagCancelled() |
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} |
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else if tagRange != nil { |
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if string == " " { |
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tagCancelled() |
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} |
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else if range.location == tagStart { |
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tagCancelled() |
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} |
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else { |
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tagExtended(to: range.location - range.length) |
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} |
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} |
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else if string == "@" { |
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if range.location == 0 { |
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tagStarted(at: range.location) |
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} |
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else if let text = textField.text, text.characters.count > 0 { |
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let sub = text[(range.location - 1)..<range.location] |
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print("Previous string: \(String(describing: sub))") |
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if sub == " " { |
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tagStarted(at: range.location) |
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} |
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} |
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} |
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print("text: \(string), range: \(NSStringFromRange(range))") |
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return true |
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} |
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func tagStarted(at location: Int) { |
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tagStart = location |
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tagRange = location..<(location + 1) |
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print("Started tag at: \(location), range: \(String(describing: tagRange))") |
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} |
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func tagExtended(to location: Int) { |
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guard let start = tagStart else { |
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fatalError("This really shouldn't happen") |
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} |
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tagRange = start..<(location + 1) |
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print("Continued tag at: \(location), range: \(String(describing: tagRange))") |
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} |
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func tagCancelled() { |
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tagStart = nil |
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tagRange = nil |
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print("Tag cancelled") |
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} |
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} |
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class TextFieldTarget: NSObject { |
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func setTargetForTextField(tf: UITextField) { |
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tf.addTarget(self, action: #selector(textFieldChanged(_:)), for: .editingChanged) |
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} |
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func textFieldChanged(_ sender: UITextField) { |
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if let range = t.tagRange, let text = sender.text { |
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print("text: \(text[range])") |
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} |
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} |
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} |
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let target = TextFieldTarget() |
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let t = Tagger() |
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let tf = UITextField(frame: CGRect(x: 0, y: 100, width: 200, height: 30)) |
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tf.backgroundColor = .gray |
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tf.textColor = .white |
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tf.delegate = t |
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target.setTargetForTextField(tf: tf) |
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PlaygroundPage.current.liveView = tf |
