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
我不知道为什么人们会把这个问题复杂化....这是相当直接和简单的。下面是UITextView的一个子类,它提供了所请求的功能。
- (void)customInit
{
self.contentMode = UIViewContentModeRedraw;
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textChanged:) name:UITextViewTextDidChangeNotification object:nil];
}
- (void)textChanged:(NSNotification *)notification
{
if (notification.object == self) {
if(self.textStorage.length != 0 || !self.textStorage.length) {
[self setNeedsDisplay];
}
}
}
#pragma mark - Setters
- (void)setPlaceholderText:(NSString *)placeholderText withFont:(UIFont *)font
{
self.placeholderText = placeholderText;
self.placeholderTextFont = font;
}
- (void)drawRect:(CGRect)rect
{
[super drawRect:rect];
[[UIColor lightGrayColor] setFill];
if (self.textStorage.length != 0) {
return;
}
CGRect inset = CGRectInset(rect, 8, 8);//Default rect insets for textView
NSDictionary *attributes = @{NSFontAttributeName: self.placeholderTextFont, NSForegroundColorAttributeName: [UIColor grayColor]};
[self.placeholderText drawInRect:inset withAttributes:attributes];
}`
其他回答
没有这样的属性在ios添加占位符直接在TextView,而你可以添加一个标签和显示/隐藏在TextView的变化。SWIFT 2.0,确保实现textviewdelegate
func textViewDidChange(TextView: UITextView)
{
if txtShortDescription.text == ""
{
self.lblShortDescription.hidden = false
}
else
{
self.lblShortDescription.hidden = true
}
}
我相信这是一个非常干净的解决方案。它在实际文本视图下面添加了一个虚拟文本视图,并根据实际文本视图中的文本显示或隐藏它:
import Foundation
import UIKit
class TextViewWithPlaceholder: UITextView {
private var placeholderTextView: UITextView = UITextView()
var placeholder: String? {
didSet {
placeholderTextView.text = placeholder
}
}
override var text: String! {
didSet {
placeholderTextView.isHidden = text.isEmpty == false
}
}
override init(frame: CGRect, textContainer: NSTextContainer?) {
super.init(frame: frame, textContainer: textContainer)
commonInit()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
commonInit()
}
private func commonInit() {
applyCommonTextViewAttributes(to: self)
configureMainTextView()
addPlaceholderTextView()
NotificationCenter.default.addObserver(self,
selector: #selector(textDidChange),
name: UITextView.textDidChangeNotification,
object: nil)
}
func addPlaceholderTextView() {
applyCommonTextViewAttributes(to: placeholderTextView)
configurePlaceholderTextView()
insertSubview(placeholderTextView, at: 0)
}
private func applyCommonTextViewAttributes(to textView: UITextView) {
textView.translatesAutoresizingMaskIntoConstraints = false
textView.textContainer.lineFragmentPadding = 0
textView.textContainerInset = UIEdgeInsets(top: 10,
left: 10,
bottom: 10,
right: 10)
}
private func configureMainTextView() {
// Do any configuration of the actual text view here
}
private func configurePlaceholderTextView() {
placeholderTextView.text = placeholder
placeholderTextView.font = font
placeholderTextView.textColor = UIColor.lightGray
placeholderTextView.frame = bounds
placeholderTextView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
}
override func layoutSubviews() {
super.layoutSubviews()
placeholderTextView.frame = bounds
}
@objc func textDidChange() {
placeholderTextView.isHidden = !text.isEmpty
}
}
var placeholderLabel : UILabel!
textviewDescription.delegate = self
placeholderLabel = UILabel()
placeholderLabel.text = "Add a description"
func textViewDidChange(_ textView: UITextView) {
placeholderLabel.isHidden = !textviewDescription.text.isEmpty
}
斯威夫特3.1
这个扩展为我工作得很好:https://github.com/devxoul/UITextView-Placeholder
下面是一个代码片段:
通过pod安装:
pod 'UITextView+Placeholder', '~> 1.2'
将它导入到类中
import UITextView_Placeholder
并添加占位符属性到您已经创建的UITextView
textView.placeholder = "Put some detail"
这是…… 这里是它的外观(第三个框是一个UITextView)
有我的简单版本的UITextView与占位符。主要思想是:
隐藏占位符,如果用户开始编辑和占位符是可见的 如果用户结束编辑并且文本视图的文本为空,则显示占位符。
class PlaceholderTextView: UITextView {
var placeholder = "" {
didSet {
if isPlaceholderVisible {
showPlaceholder()
}
}
}
var isPlaceholderVisible = true {
didSet {
isPlaceholderVisible ? showPlaceholder() : hidePlaceholder()
}
}
init() {
super.init(frame: .zero, textContainer: nil)
delegate = self
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
private func showPlaceholder() {
text = placeholder
// Set other things like color of text for placeholder, ...
}
private func hidePlaceholder() {
text = ""
// Set other things like color of text for normal input, ...
}
}
extension PlaceholderTextView: UITextViewDelegate {
func textViewDidBeginEditing(_ textView: UITextView) {
if isPlaceholderVisible {
isPlaceholderVisible = false
}
}
func textViewDidEndEditing(_ textView: UITextView) {
if text.isEmpty {
isPlaceholderVisible = true
}
}
}
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