在UITextView内添加占位符文本在Swift?

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

斯威夫特3.2

extension EditProfileVC:UITextViewDelegate{

    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 = "Placeholder"
            textView.textColor = UIColor.lightGray
        }
    }
}

首先，当用户开始编辑textViewDidBeginEditing调用，然后检查如果文本灰色的颜色意味着用户没有写任何东西，然后设置为textview nil，并将用户文本的颜色更改为黑色。

当用户端编辑textViewDidEndEditing是调用和检查如果用户没有写任何在textview然后文本设置为灰色与文本“占位符”

2017-12-07 07:16:03

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

2017-04-27 06:17:19

在视图加载中设置值

    txtVw!.autocorrectionType = UITextAutocorrectionType.No
    txtVw!.text = "Write your Placeholder"
    txtVw!.textColor = UIColor.lightGrayColor()



func textViewDidBeginEditing(textView: UITextView) {
    if (txtVw?.text == "Write your Placeholder")

    {
        txtVw!.text = nil
        txtVw!.textColor = UIColor.blackColor()
    }
}

func textViewDidEndEditing(textView: UITextView) {
    if txtVw!.text.isEmpty
    {
        txtVw!.text = "Write your Placeholder"
        txtVw!.textColor = UIColor.lightGrayColor()
    }
    textView.resignFirstResponder()
}

2015-09-01 10:34:30

我知道这是一个老问题，但想分享我认为是一个有用的方式扩展UITextView有placeholderText和placeholderColor字段。基本上你将UITextView转换为UITextField，然后设置attributedPlaceholder字段。PlaceholderText和placeholderColor是IBInspectable字段，所以它们的值可以在IB中设置，并与UITextField占位符功能完全相同。

UITextView+Extend.h

#import <UIKit/UIKit.h>

@interface UITextView (Extend)

@property (nonatomic) IBInspectable NSString *placeholderText;
@property (nonatomic) IBInspectable UIColor *placeholderColor;

@end

UITextView+Extend.m

#import "UITextView+Extend.h"
#import "objc/runtime.h"

@implementation UITextView (Extend)

- (void)setPlaceholderText:(NSString *)placeholderText
{
    objc_setAssociatedObject(self, @selector(placeholderText), placeholderText, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    [self updatePlaceholderText];
}

- (NSString*)placeholderText
{
    return objc_getAssociatedObject(self, @selector(placeholderText));
}

- (void)setPlaceholderColor:(UIColor *)placeholderColor
{
    objc_setAssociatedObject(self, @selector(placeholderColor), placeholderColor, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    [self updatePlaceholderText];
}

- (UIColor*)placeholderColor
{
    return objc_getAssociatedObject(self, @selector(placeholderColor));
}

- (void)updatePlaceholderText
{
    NSString *text = self.placeholderText;
    UIColor *color = self.placeholderColor;
    if(text && color)
    {
        UITextField *textField = (UITextField*)self;
        textField.attributedPlaceholder = [[NSAttributedString alloc] initWithString:text attributes:@{NSForegroundColorAttributeName:color}];
    }
}

@end

2019-10-25 06:50:53

在swift2.2:

public class CustomTextView: UITextView {

private struct Constants {
    static let defaultiOSPlaceholderColor = UIColor(red: 0.0, green: 0.0, blue: 0.0980392, alpha: 0.22)
}
private let placeholderLabel: UILabel = UILabel()

private var placeholderLabelConstraints = [NSLayoutConstraint]()

@IBInspectable public var placeholder: String = "" {
    didSet {
        placeholderLabel.text = placeholder
    }
}

@IBInspectable public var placeholderColor: UIColor = CustomTextView.Constants.defaultiOSPlaceholderColor {
    didSet {
        placeholderLabel.textColor = placeholderColor
    }
}

override public var font: UIFont! {
    didSet {
        placeholderLabel.font = font
    }
}

override public var textAlignment: NSTextAlignment {
    didSet {
        placeholderLabel.textAlignment = textAlignment
    }
}

override public var text: String! {
    didSet {
        textDidChange()
    }
}

override public var attributedText: NSAttributedString! {
    didSet {
        textDidChange()
    }
}

override public var textContainerInset: UIEdgeInsets {
    didSet {
        updateConstraintsForPlaceholderLabel()
    }
}

override public init(frame: CGRect, textContainer: NSTextContainer?) {
    super.init(frame: frame, textContainer: textContainer)
    commonInit()
}

required public init?(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
    commonInit()
}

private func commonInit() {
    NSNotificationCenter.defaultCenter().addObserver(self,
                                                     selector: #selector(textDidChange),
                                                     name: UITextViewTextDidChangeNotification,
                                                     object: nil)

    placeholderLabel.font = font
    placeholderLabel.textColor = placeholderColor
    placeholderLabel.textAlignment = textAlignment
    placeholderLabel.text = placeholder
    placeholderLabel.numberOfLines = 0
    placeholderLabel.backgroundColor = UIColor.clearColor()
    placeholderLabel.translatesAutoresizingMaskIntoConstraints = false
    addSubview(placeholderLabel)
    updateConstraintsForPlaceholderLabel()
}

private func updateConstraintsForPlaceholderLabel() {
    var newConstraints = NSLayoutConstraint.constraintsWithVisualFormat("H:|-(\(textContainerInset.left + textContainer.lineFragmentPadding))-[placeholder]",
                                                                        options: [],
                                                                        metrics: nil,
                                                                        views: ["placeholder": placeholderLabel])
    newConstraints += NSLayoutConstraint.constraintsWithVisualFormat("V:|-(\(textContainerInset.top))-[placeholder]",
                                                                     options: [],
                                                                     metrics: nil,
                                                                     views: ["placeholder": placeholderLabel])
    newConstraints.append(NSLayoutConstraint(
        item: placeholderLabel,
        attribute: .Width,
        relatedBy: .Equal,
        toItem: self,
        attribute: .Width,
        multiplier: 1.0,
        constant: -(textContainerInset.left + textContainerInset.right + textContainer.lineFragmentPadding * 2.0)
        ))
    removeConstraints(placeholderLabelConstraints)
    addConstraints(newConstraints)
    placeholderLabelConstraints = newConstraints
}

@objc private func textDidChange() {
    placeholderLabel.hidden = !text.isEmpty
}

public override func layoutSubviews() {
    super.layoutSubviews()
    placeholderLabel.preferredMaxLayoutWidth = textContainer.size.width - textContainer.lineFragmentPadding * 2.0
}

deinit {
    NSNotificationCenter.defaultCenter().removeObserver(self,
                                                        name: UITextViewTextDidChangeNotification,
                                                        object: nil)
}

}

在swift3:

import UIKit

类 CustomTextView： { UITextView

private struct Constants {
    static let defaultiOSPlaceholderColor = UIColor(red: 0.0, green: 0.0, blue: 0.0980392, alpha: 0.22)
}
private let placeholderLabel: UILabel = UILabel()

private var placeholderLabelConstraints = [NSLayoutConstraint]()

@IBInspectable public var placeholder: String = "" {
    didSet {
        placeholderLabel.text = placeholder
    }
}

@IBInspectable public var placeholderColor: UIColor = CustomTextView.Constants.defaultiOSPlaceholderColor {
    didSet {
        placeholderLabel.textColor = placeholderColor
    }
}

override public var font: UIFont! {
    didSet {
        placeholderLabel.font = font
    }
}

override public var textAlignment: NSTextAlignment {
    didSet {
        placeholderLabel.textAlignment = textAlignment
    }
}

override public var text: String! {
    didSet {
        textDidChange()
    }
}

override public var attributedText: NSAttributedString! {
    didSet {
        textDidChange()
    }
}

override public var textContainerInset: UIEdgeInsets {
    didSet {
        updateConstraintsForPlaceholderLabel()
    }
}

override public init(frame: CGRect, textContainer: NSTextContainer?) {
    super.init(frame: frame, textContainer: textContainer)
    commonInit()
}

required public init?(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
    commonInit()
}

private func commonInit() {
    NotificationCenter.default.addObserver(self,
                                                     selector: #selector(textDidChange),
                                                     name: NSNotification.Name.UITextViewTextDidChange,
                                                     object: nil)

    placeholderLabel.font = font
    placeholderLabel.textColor = placeholderColor
    placeholderLabel.textAlignment = textAlignment
    placeholderLabel.text = placeholder
    placeholderLabel.numberOfLines = 0
    placeholderLabel.backgroundColor = UIColor.clear
    placeholderLabel.translatesAutoresizingMaskIntoConstraints = false
    addSubview(placeholderLabel)
    updateConstraintsForPlaceholderLabel()
}

private func updateConstraintsForPlaceholderLabel() {
    var newConstraints = NSLayoutConstraint.constraints(withVisualFormat: "H:|-(\(textContainerInset.left + textContainer.lineFragmentPadding))-[placeholder]",
        options: [],
        metrics: nil,
        views: ["placeholder": placeholderLabel])
    newConstraints += NSLayoutConstraint.constraints(withVisualFormat: "V:|-(\(textContainerInset.top))-[placeholder]",
        options: [],
        metrics: nil,
        views: ["placeholder": placeholderLabel])
    newConstraints.append(NSLayoutConstraint(
        item: placeholderLabel,
        attribute: .width,
        relatedBy: .equal,
        toItem: self,
        attribute: .width,
        multiplier: 1.0,
        constant: -(textContainerInset.left + textContainerInset.right + textContainer.lineFragmentPadding * 2.0)
    ))
    removeConstraints(placeholderLabelConstraints)
    addConstraints(newConstraints)
    placeholderLabelConstraints = newConstraints
}

@objc private func textDidChange() {
    placeholderLabel.isHidden = !text.isEmpty
}

public override func layoutSubviews() {
    super.layoutSubviews()
    placeholderLabel.preferredMaxLayoutWidth = textContainer.size.width - textContainer.lineFragmentPadding * 2.0
}

deinit {
    NotificationCenter.default.removeObserver(self,
                                                        name: NSNotification.Name.UITextViewTextDidChange,
                                                        object: nil)
}

}

我用swift写了一个类。您需要在需要的时候导入这个类。

2016-12-27 12:12:37

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
        }
    }
}

2020-03-16 11:23:48

在UITextView内添加占位符文本在Swift?

推荐文章

最新文章

标签