Fix topic cell, introduce PlaceholderedTextView

2026-05-02 06:06:57 +02:00 · 2020-09-10 18:14:19 +03:00
parent 17bd6b0bf3
commit 68d464cfe5
5 changed files with 224 additions and 14 deletions
@@ -0,0 +1,119 @@
+// 
+// Copyright 2020 New Vector Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import UIKit
+
+class PlaceholderedTextView: UITextView {
+    
+    private var kvoLineFragmentPadding: NSKeyValueObservation?
+    private lazy var placeholderTextView: UITextView = {
+        let view = UITextView()
+        view.contentInset = self.contentInset
+        view.textContainerInset = self.textContainerInset
+        view.textContainer.lineFragmentPadding = self.textContainer.lineFragmentPadding
+        view.scrollsToTop = false
+        view.showsVerticalScrollIndicator = false
+        view.showsHorizontalScrollIndicator = false
+        view.isEditable = false
+        view.isSelectable = false
+        view.isScrollEnabled = false
+        view.textColor = self.placeholderColor
+        if let placeholder = self.placeholder {
+            view.text = placeholder
+        } else if let attributedPlaceholder = self.attributedPlaceholder {
+            view.attributedText = attributedPlaceholder
+        }
+        view.backgroundColor = .clear
+        view.tintColor = .clear
+        self.addSubview(view)
+        self.sendSubviewToBack(view)
+        return view
+    }()
+    
+    var placeholder: String? {
+        didSet {
+            placeholderTextView.text = placeholder
+        }
+    }
+    var attributedPlaceholder: NSAttributedString? {
+        didSet {
+            placeholderTextView.attributedText = attributedPlaceholder
+        }
+    }
+    var placeholderColor: UIColor = .lightGray {
+        didSet {
+            placeholderTextView.textColor = placeholderColor
+        }
+    }
+    
+    override var font: UIFont? {
+        didSet {
+            placeholderTextView.font = font
+        }
+    }
+    
+    override var contentInset: UIEdgeInsets {
+        didSet {
+            placeholderTextView.contentInset = contentInset
+        }
+    }
+    
+    override var textContainerInset: UIEdgeInsets {
+        didSet {
+            placeholderTextView.textContainerInset = textContainerInset
+        }
+    }
+    
+    override func layoutSubviews() {
+        super.layoutSubviews()
+        placeholderTextView.frame = bounds
+    }
+    
+    override init(frame: CGRect, textContainer: NSTextContainer?) {
+        super.init(frame: frame, textContainer: textContainer)
+        setup()
+    }
+
+    required init?(coder: NSCoder) {
+        super.init(coder: coder)
+        setup()
+    }
+
+    private func setup() {
+        NotificationCenter.default.addObserver(self, selector: #selector(textViewTextChanged(_:)), name: UITextView.textDidChangeNotification, object: self)
+        kvoLineFragmentPadding = observe(\.textContainer.lineFragmentPadding, options: [.new]) { [weak self] (_, change) in
+            guard let self = self else { return }
+            let newValue = change.newValue ?? 0
+            self.placeholderTextView.textContainer.lineFragmentPadding = newValue
+        }
+    }
+
+    override var text: String! {
+        didSet {
+            super.text = text
+            updatePlaceholderVisibility()
+        }
+    }
+
+    @objc func textViewTextChanged(_ sender: UITextView) {
+        updatePlaceholderVisibility()
+    }
+
+    private func updatePlaceholderVisibility() {
+        placeholderTextView.isHidden = text.count > 0
+    }
+    
+}