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
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。
其他回答
这里有一个简单而聪明的方法来获得完美的行为。
让我们借用UITextField中的占位符。
Set up a textField and set its text transparent. self.placeholderTextField = [[UITextField alloc] init]; /* adjust the frame to fit it in the first line of your textView */ self.placeholderTextField.frame = CGRectMake(0.0, 0.0, yourTextView.width, 30.0); self.placeholderTextField.textColor = [UIColor clearColor]; self.placeholderTextField.userInteractionEnabled = NO; self.placeholderTextField.font = yourTextView.font; self.placeholderTextField.placeholder = @"sample placeholder"; [yourTextView addSubview:self.placeholderTextField]; Set textView's delegate and synchronize the textField and textView. yourTextView.delegate = self; then - (void)textViewDidChange:(UITextView *)textView { self.placeholderTextField.text = textView.text; } That's all.
我创建了一个实例变量来检查是否显示占位符:
BOOL showPlaceHolder;
UITextView * textView; // and also the textView
在viewDidLoad上设置:
[self setPlaceHolder];
下面是它的作用:
- (void)setPlaceholder
{
textView.text = NSLocalizedString(@"Type your question here", @"placeholder");
textView.textColor = [UIColor lightGrayColor];
self.showPlaceHolder = YES; //we save the state so it won't disappear in case you want to re-edit it
}
我还创建了一个按钮来退出键盘。您不必这样做,但这里很酷的事情是,如果没有输入任何内容,占位符将再次显示
- (void)textViewDidBeginEditing:(UITextView *)txtView
{
self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"Done" style:UIBarButtonItemStyleDone target:self action:@selector(resignKeyboard)];
if (self.showPlaceHolder == YES)
{
textView.textColor = [UIColor blackColor];
textView.text = @"";
self.showPlaceHolder = NO;
}
}
- (void)resignKeyboard
{
[textView resignFirstResponder];
//here if you created a button like I did to resign the keyboard, you should hide it
if (textView.text.length == 0) {
[self setPlaceholder];
}
}
下面是swift 3.1的代码
原始代码由杰森乔治在第一个答案。
不要忘记设置你的自定义类的TextView在接口生成器UIPlaceHolderTextView,然后设置占位符和占位符属性。
import UIKit
@IBDesignable
class UIPlaceHolderTextView: UITextView {
@IBInspectable var placeholder: String = ""
@IBInspectable var placeholderColor: UIColor = UIColor.lightGray
private let uiPlaceholderTextChangedAnimationDuration: Double = 0.05
private let defaultTagValue = 999
private var placeHolderLabel: UILabel?
override func awakeFromNib() {
super.awakeFromNib()
NotificationCenter.default.addObserver(
self,
selector: #selector(textChanged),
name: NSNotification.Name.UITextViewTextDidChange,
object: nil
)
}
override init(frame: CGRect, textContainer: NSTextContainer?) {
super.init(frame: frame, textContainer: textContainer)
NotificationCenter.default.addObserver(
self,
selector: #selector(textChanged),
name: NSNotification.Name.UITextViewTextDidChange,
object: nil
)
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
NotificationCenter.default.addObserver(
self,
selector: #selector(textChanged),
name: NSNotification.Name.UITextViewTextDidChange,
object: nil
)
}
deinit {
NotificationCenter.default.removeObserver(
self,
name: NSNotification.Name.UITextViewTextDidChange,
object: nil
)
}
@objc private func textChanged() {
guard !placeholder.isEmpty else {
return
}
UIView.animate(withDuration: uiPlaceholderTextChangedAnimationDuration) {
if self.text.isEmpty {
self.viewWithTag(self.defaultTagValue)?.alpha = CGFloat(1.0)
}
else {
self.viewWithTag(self.defaultTagValue)?.alpha = CGFloat(0.0)
}
}
}
override var text: String! {
didSet{
super.text = text
textChanged()
}
}
override func draw(_ rect: CGRect) {
if !placeholder.isEmpty {
if placeHolderLabel == nil {
placeHolderLabel = UILabel.init(frame: CGRect(x: 0, y: 8, width: bounds.size.width - 16, height: 0))
placeHolderLabel!.lineBreakMode = .byWordWrapping
placeHolderLabel!.numberOfLines = 0
placeHolderLabel!.font = font
placeHolderLabel!.backgroundColor = UIColor.clear
placeHolderLabel!.textColor = placeholderColor
placeHolderLabel!.alpha = 0
placeHolderLabel!.tag = defaultTagValue
self.addSubview(placeHolderLabel!)
}
placeHolderLabel!.text = placeholder
placeHolderLabel!.sizeToFit()
self.sendSubview(toBack: placeHolderLabel!)
if text.isEmpty && !placeholder.isEmpty {
viewWithTag(defaultTagValue)?.alpha = 1.0
}
}
super.draw(rect)
}
}
好吧,我的阴沟有点不同 我创建了一个小班来为你做这件事。
TextViewShader。m文件
#import "TextViewShader.h"
@implementation TextViewShader
-(id)initWithShadedTextView:(NSString *)text textViewToShade:(UITextView *)textview {
self = [super initWithFrame:textview.frame];
if (self) {
if (shadeLabel==nil)
{
shadeLabel= [[UILabel alloc]initWithFrame:CGRectMake(10, 0, textview.frame.size.width, 30)];
}
shadeLabel.text =text;// @"Enter Your Support Request";
shadeLabel.textColor = [UIColor lightGrayColor];
[textview setDelegate: self];
[textview addSubview:shadeLabel];
}
return self;
}
-(void)textViewDidChange:(UITextView *)textView{
if (textView.text.length==0)
{
shadeLabel.hidden=false;
}
else
{
shadeLabel.hidden=true;
}
}
@end
TextViewShader.h文件
#import <UIKit/UIKit.h>
@interface TextViewShader : UIView<UITextViewDelegate>{
UILabel *shadeLabel;
}
-(id)initWithShadedTextView:(NSString *)text textViewToShade:(UITextView *)textview ;
@end
这是简单的一行代码使用(不要忘记添加#import "TextViewShader.h")
TextViewShader* shader = [[TextViewShader alloc]initWithShadedTextView:@"Enter Your Support Request" textViewToShade: youruitextviewToshade];
玩得开心!
在UITextView中创建占位符是不可能的,但是你可以通过这个生成类似占位符的效果。
- (void)viewDidLoad{
commentTxtView.text = @"Comment";
commentTxtView.textColor = [UIColor lightGrayColor];
commentTxtView.delegate = self;
}
- (BOOL) textViewShouldBeginEditing:(UITextView *)textView
{
commentTxtView.text = @"";
commentTxtView.textColor = [UIColor blackColor];
return YES;
}
-(void) textViewDidChange:(UITextView *)textView
{
if(commentTxtView.text.length == 0){
commentTxtView.textColor = [UIColor lightGrayColor];
commentTxtView.text = @"Comment";
[commentTxtView resignFirstResponder];
}
}
或者你可以添加标签在textview就像
lbl = [[UILabel alloc] initWithFrame:CGRectMake(10.0, 0.0,textView.frame.size.width - 10.0, 34.0)];
[lbl setText:kDescriptionPlaceholder];
[lbl setBackgroundColor:[UIColor clearColor]];
[lbl setTextColor:[UIColor lightGrayColor]];
textView.delegate = self;
[textView addSubview:lbl];
并设置
- (void)textViewDidEndEditing:(UITextView *)theTextView
{
if (![textView hasText]) {
lbl.hidden = NO;
}
}
- (void) textViewDidChange:(UITextView *)textView
{
if(![textView hasText]) {
lbl.hidden = NO;
}
else{
lbl.hidden = YES;
}
}