我的应用程序使用UITextView。现在我想让UITextView有一个占位符,类似于你可以为UITextField设置的占位符。
如何做到这一点?
我的应用程序使用UITextView。现在我想让UITextView有一个占位符,类似于你可以为UITextField设置的占位符。
如何做到这一点?
当前回答
你能做的是在文本属性中设置文本视图的初始值,并将textColor更改为[UIColor grayColor]或类似的东西。然后,每当文本视图变为可编辑时,清除文本并显示游标,如果文本字段再次为空,则将占位符文本放回。根据需要将颜色更改为[UIColor blackColor]。
它与UITextField中的占位符功能不完全相同,但很接近。
其他回答
在看完所有答案后,我意识到我需要一些简单的,同时可重用的东西,这样我就可以在我的项目中为所有uitextview添加相同的功能。最后我得到了以下代码:
extension UITextView {
// MARK: TextView PlaceHolderLabel Setup
func createPlaceHolderLabel(with text: String) {
let lbl = UILabel()
self.addSubview(lbl)
// Add your constraints here
lbl.text = text
lbl.textColor = .lightGray
}
// My Textview contains only one UILabel, and for my use case the below code works, tweak it according to your use case
// Lastly two methods to toggle between show and hide the placeholder label
func hidePlaceHolderLabel() {
guard let lbl = self.subviews.first(where: { $0 is UILabel }) else { return }
lbl.isHidden = true
}
func showPlaceHolderLabel() {
guard let lbl = self.subviews.first(where: { $0 is UILabel }) else { return }
lbl.isHidden = false
}
}
当UILabel作为子视图添加到UITextView时,textView游标位置和UILabel位置将不匹配,因此在占位符文本之前留下一个空间
class ViewController: UIViewController, UITextViewDelegate {
var textView: UITextView!
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(textView)
// Also setup textView constraints as per your need
// Add placeholder to your textView
// Leave one space before placeholder string
textView.createPlaceHolderLabel(with: " Address")
textView.delegate = self
}
然后在textViewdidChange方法中添加以下代码
func textViewDidChange(_ textView: UITextView) {
if textView.text.isEmpty {
textView.showPlaceHolderLabel()
} else {
textView.hidePlaceHolderLabel()
}
}
它可以在所有uitextview中重用。
简单的Swift 3解决方案
添加UITextViewDelegate到类中
设置你的textview .delegate = self
创建placeholderLabel和位置它在你的textview
现在动画placeholderLabel。alpha在textViewDidChange:
func textViewDidChange(_ textView: UITextView) {
let newAlpha: CGFloat = textView.text.isEmpty ? 1 : 0
if placeholderLabel.alpha != newAlpha {
UIView.animate(withDuration: 0.3) {
self.placeholderLabel.alpha = newAlpha
}
}
}
你可能不得不使用placeholderLabel位置来设置它,但这应该不会太难
你能做的是在文本属性中设置文本视图的初始值,并将textColor更改为[UIColor grayColor]或类似的东西。然后,每当文本视图变为可编辑时,清除文本并显示游标,如果文本字段再次为空,则将占位符文本放回。根据需要将颜色更改为[UIColor blackColor]。
它与UITextField中的占位符功能不完全相同,但很接近。
我已经创建了一个快速3版本的最高排名的答案
你只需要做UITextView的子类化。
import UIKit
class UIPlaceHolderTextView: UITextView {
//MARK: - Properties
@IBInspectable var placeholder: String?
@IBInspectable var placeholderColor: UIColor?
var placeholderLabel: UILabel?
//MARK: - Initializers
override func awakeFromNib() {
super.awakeFromNib()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
// Use Interface Builder User Defined Runtime Attributes to set
// placeholder and placeholderColor in Interface Builder.
if self.placeholder == nil {
self.placeholder = ""
}
if self.placeholderColor == nil {
self.placeholderColor = UIColor.black
}
NotificationCenter.default.addObserver(self, selector: #selector(textChanged(_:)), name: NSNotification.Name.UITextViewTextDidChange, object: nil)
}
func textChanged(_ notification: Notification) -> Void {
if self.placeholder?.count == 0 {
return
}
UIView.animate(withDuration: 0.25) {
if self.text.count == 0 {
self.viewWithTag(999)?.alpha = 1
}
else {
self.viewWithTag(999)?.alpha = 0
}
}
}
// Only override draw() if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
override func draw(_ rect: CGRect) {
super.draw(rect)
if (self.placeholder?.count ?? 0) > 0 {
if placeholderLabel == nil {
placeholderLabel = UILabel.init()
placeholderLabel?.lineBreakMode = .byWordWrapping
placeholderLabel?.numberOfLines = 0
placeholderLabel?.font = self.font
placeholderLabel?.backgroundColor = self.backgroundColor
placeholderLabel?.textColor = self.placeholderColor
placeholderLabel?.alpha = 0
placeholderLabel?.tag = 999
self.addSubview(placeholderLabel!)
placeholderLabel?.translatesAutoresizingMaskIntoConstraints = false
placeholderLabel?.topAnchor.constraint(equalTo: self.topAnchor, constant: 7).isActive = true
placeholderLabel?.leftAnchor.constraint(equalTo: self.leftAnchor, constant: 4).isActive = true
placeholderLabel?.bottomAnchor.constraint(equalTo: self.bottomAnchor).isActive = true
placeholderLabel?.rightAnchor.constraint(equalTo: self.rightAnchor).isActive = true
}
placeholderLabel?.text = self.placeholder
placeholderLabel?.sizeToFit()
self.sendSubview(toBack: self.placeholderLabel!)
}
if self.text.count == 0 && (self.placeholder?.count ?? 0) > 0 {
self.viewWithTag(999)?.alpha = 1
}
}
}
如果有人需要Swift的解决方案:
添加UITextViewDelegate到类中
var placeHolderText = "Placeholder Text..."
override func viewDidLoad() {
super.viewDidLoad()
textView.delegate = self
}
func textViewShouldBeginEditing(textView: UITextView) -> Bool {
self.textView.textColor = .black
if(self.textView.text == placeHolderText) {
self.textView.text = ""
}
return true
}
func textViewDidEndEditing(textView: UITextView) {
if(textView.text == "") {
self.textView.text = placeHolderText
self.textView.textColor = .lightGray
}
}
override func viewWillAppear(animated: Bool) {
if(currentQuestion.answerDisplayValue == "") {
self.textView.text = placeHolderText
self.textView.textColor = .lightGray
} else {
self.textView.text = "xxx" // load default text / or stored
self.textView.textColor = .black
}
}