如何在UITextView中添加占位符,类似于你可以为UITextField设置的占位符,在Swift中?
当前回答
还有一个解决方案(Swift 3):
import UIKit
protocol PlaceholderTextViewDelegate {
func placeholderTextViewDidChangeText(_ text:String)
func placeholderTextViewDidEndEditing(_ text:String)
}
final class PlaceholderTextView: UITextView {
var notifier:PlaceholderTextViewDelegate?
var placeholder: String? {
didSet {
placeholderLabel?.text = placeholder
}
}
var placeholderColor = UIColor.lightGray
var placeholderFont = UIFont.appMainFontForSize(14.0) {
didSet {
placeholderLabel?.font = placeholderFont
}
}
fileprivate var placeholderLabel: UILabel?
// MARK: - LifeCycle
init() {
super.init(frame: CGRect.zero, textContainer: nil)
awakeFromNib()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
override func awakeFromNib() {
super.awakeFromNib()
self.delegate = self
NotificationCenter.default.addObserver(self, selector: #selector(PlaceholderTextView.textDidChangeHandler(notification:)), name: .UITextViewTextDidChange, object: nil)
placeholderLabel = UILabel()
placeholderLabel?.textColor = placeholderColor
placeholderLabel?.text = placeholder
placeholderLabel?.textAlignment = .left
placeholderLabel?.numberOfLines = 0
}
override func layoutSubviews() {
super.layoutSubviews()
placeholderLabel?.font = placeholderFont
var height:CGFloat = placeholderFont.lineHeight
if let data = placeholderLabel?.text {
let expectedDefaultWidth:CGFloat = bounds.size.width
let fontSize:CGFloat = placeholderFont.pointSize
let textView = UITextView()
textView.text = data
textView.font = UIFont.appMainFontForSize(fontSize)
let sizeForTextView = textView.sizeThatFits(CGSize(width: expectedDefaultWidth,
height: CGFloat.greatestFiniteMagnitude))
let expectedTextViewHeight = sizeForTextView.height
if expectedTextViewHeight > height {
height = expectedTextViewHeight
}
}
placeholderLabel?.frame = CGRect(x: 5, y: 0, width: bounds.size.width - 16, height: height)
if text.isEmpty {
addSubview(placeholderLabel!)
bringSubview(toFront: placeholderLabel!)
} else {
placeholderLabel?.removeFromSuperview()
}
}
func textDidChangeHandler(notification: Notification) {
layoutSubviews()
}
}
extension PlaceholderTextView : UITextViewDelegate {
// MARK: - UITextViewDelegate
func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
if(text == "\n") {
textView.resignFirstResponder()
return false
}
return true
}
func textViewDidChange(_ textView: UITextView) {
notifier?.placeholderTextViewDidChangeText(textView.text)
}
func textViewDidEndEditing(_ textView: UITextView) {
notifier?.placeholderTextViewDidEndEditing(textView.text)
}
}
结果
其他回答
还有一个解决方案(Swift 3):
import UIKit
protocol PlaceholderTextViewDelegate {
func placeholderTextViewDidChangeText(_ text:String)
func placeholderTextViewDidEndEditing(_ text:String)
}
final class PlaceholderTextView: UITextView {
var notifier:PlaceholderTextViewDelegate?
var placeholder: String? {
didSet {
placeholderLabel?.text = placeholder
}
}
var placeholderColor = UIColor.lightGray
var placeholderFont = UIFont.appMainFontForSize(14.0) {
didSet {
placeholderLabel?.font = placeholderFont
}
}
fileprivate var placeholderLabel: UILabel?
// MARK: - LifeCycle
init() {
super.init(frame: CGRect.zero, textContainer: nil)
awakeFromNib()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
override func awakeFromNib() {
super.awakeFromNib()
self.delegate = self
NotificationCenter.default.addObserver(self, selector: #selector(PlaceholderTextView.textDidChangeHandler(notification:)), name: .UITextViewTextDidChange, object: nil)
placeholderLabel = UILabel()
placeholderLabel?.textColor = placeholderColor
placeholderLabel?.text = placeholder
placeholderLabel?.textAlignment = .left
placeholderLabel?.numberOfLines = 0
}
override func layoutSubviews() {
super.layoutSubviews()
placeholderLabel?.font = placeholderFont
var height:CGFloat = placeholderFont.lineHeight
if let data = placeholderLabel?.text {
let expectedDefaultWidth:CGFloat = bounds.size.width
let fontSize:CGFloat = placeholderFont.pointSize
let textView = UITextView()
textView.text = data
textView.font = UIFont.appMainFontForSize(fontSize)
let sizeForTextView = textView.sizeThatFits(CGSize(width: expectedDefaultWidth,
height: CGFloat.greatestFiniteMagnitude))
let expectedTextViewHeight = sizeForTextView.height
if expectedTextViewHeight > height {
height = expectedTextViewHeight
}
}
placeholderLabel?.frame = CGRect(x: 5, y: 0, width: bounds.size.width - 16, height: height)
if text.isEmpty {
addSubview(placeholderLabel!)
bringSubview(toFront: placeholderLabel!)
} else {
placeholderLabel?.removeFromSuperview()
}
}
func textDidChangeHandler(notification: Notification) {
layoutSubviews()
}
}
extension PlaceholderTextView : UITextViewDelegate {
// MARK: - UITextViewDelegate
func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
if(text == "\n") {
textView.resignFirstResponder()
return false
}
return true
}
func textViewDidChange(_ textView: UITextView) {
notifier?.placeholderTextViewDidChangeText(textView.text)
}
func textViewDidEndEditing(_ textView: UITextView) {
notifier?.placeholderTextViewDidEndEditing(textView.text)
}
}
结果
Swift 4、4.2和5
[![@IBOutlet var detailTextView: UITextView!
override func viewDidLoad() {
super.viewDidLoad()
detailTextView.delegate = self
}
extension ContactUsViewController : UITextViewDelegate {
public func textViewDidBeginEditing(_ textView: UITextView) {
if textView.text == "Write your message here..." {
detailTextView.text = ""
detailTextView.textColor = UIColor.init(red: 0/255, green: 0/255, blue: 0/255, alpha: 0.86)
}
textView.becomeFirstResponder()
}
public func textViewDidEndEditing(_ textView: UITextView) {
if textView.text == "" {
detailTextView.text = "Write your message here..."
detailTextView.textColor = UIColor.init(red: 0/255, green: 0/255, blue: 0/255, alpha: 0.30)
}
textView.resignFirstResponder()
}
[![}][1]][1]
var placeholderLabel : UILabel!
textviewDescription.delegate = self
placeholderLabel = UILabel()
placeholderLabel.text = "Add a description"
func textViewDidChange(_ textView: UITextView) {
placeholderLabel.isHidden = !textviewDescription.text.isEmpty
}
import UIKit
import RxSwift
@IBDesignable class TextViewWithPlaceholder: UITextView {
//MARK: - Propertise
@IBInspectable var placeholderText: String = ""
let placeholderLabel = LocalizedUILabel()
private let hidePlaceholderObserver = PublishSubject<Bool>()
let disposeBag = DisposeBag()
//MARK: - Did Move To Window
override func didMoveToWindow() {
super.didMoveToWindow()
observeOnTextViewEditing()
configurePlaceholder()
}
//MARK: - Observe On Text View Editing
private func observeOnTextViewEditing() {
rx.text.subscribe(onNext: { [weak self] selectedText in
guard let self = self else { return }
self.hidePlaceholderObserver.onNext((selectedText?.isEmpty ?? true) ? false : true)
}).disposed(by: disposeBag)
}
//MARK: - Observe On Show Hide Placeholder
private func configurePlaceholder() {
hidePlaceholderObserver
.bind(to: placeholderLabel.rx.isHidden)
.disposed(by: disposeBag)
placeholderLabel.text = placeholderText
placeholderLabel.font = UIFont(name: "Poppins-Semibold", size: 16) ?? UIFont()
placeholderLabel.textColor = .lightGray
placeholderLabel.sizeToFit()
placeholderLabel.frame.origin = CGPoint(x: 8, y: 8)
addSubview(placeholderLabel)
}
}
斯威夫特
这是一个Swiftui TextView使用UIVIewRepresentable,具有占位符功能和边界颜色
struct TextView: UIViewRepresentable {
@Binding var text: String
var placeholderText: String
var textStyle: UIFont.TextStyle
func makeUIView(context: Context) -> UITextView {
let textView = UITextView()
textView.font = UIFont.preferredFont(forTextStyle: textStyle)
textView.autocapitalizationType = .sentences
textView.isSelectable = true
textView.isUserInteractionEnabled = true
textView.delegate = context.coordinator
textView.layer.borderWidth = 0.6
textView.layer.borderColor = UIColor.lightGray.cgColor
textView.layer.cornerRadius = 10
textView.text = placeholderText
textView.textColor = UIColor.lightGray
return textView
}
func updateUIView(_ uiView: UITextView, context: Context) {
uiView.text = text
uiView.font = UIFont.preferredFont(forTextStyle: textStyle)
}
func makeCoordinator() -> Coordinator {
Coordinator(self)
}
class Coordinator: NSObject, UITextViewDelegate {
var parent: TextView
init(_ parent: TextView) {
self.parent = parent
}
func textViewDidChange(_ textView: UITextView) {
self.parent.text = textView.text
}
func textViewDidBeginEditing(_ textView: UITextView) {
if textView.textColor == UIColor.lightGray {
textView.text = nil
textView.textColor = UIColor.black
}
}
func textViewDidEndEditing(_ textView: UITextView) {
if textView.text.isEmpty {
textView.text = self.parent.placeholderText
textView.textColor = UIColor.lightGray
}
}
}
}
然后在你的视图中你可以这样使用它
TextView(text: self.$viewModel.addPostCommentText, placeholderText: "Share your story about this cash", textStyle: .body)
.padding()
.frame(height: 150)
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