在UITextView PlaceholderTextView中支持图标属性占位符的简单类

@IBOutlet weak var tvMessage: PlaceholderTextView!
//  TODO: - Create Icon Text Attachment
let icon: NSTextAttachment = NSTextAttachment()
icon.image = UIImage(named: "paper-plane")
let iconString = NSMutableAttributedString(attributedString: NSAttributedString(attachment: icon))

tvMessage.icon = icon

//  TODO: - Attributes
let textColor = UIColor.gray
let lightFont = UIFont(name: "Helvetica-Light", size: tvMessage.font!.pointSize)
let italicFont = UIFont(name: "Helvetica-LightOblique", size: tvMessage.font!.pointSize)

//  TODO: - Placeholder Attributed String
let message = NSAttributedString(string: " " + "Personal Message", attributes: [ NSFontAttributeName: lightFont!,   NSForegroundColorAttributeName: textColor])
iconString.append(message)
// TODO: - Italic Placeholder Part
let option = NSAttributedString(string: " " + "Optional", attributes: [ NSFontAttributeName: italicFont!, NSForegroundColorAttributeName: textColor])
iconString.append(option)

tvMessage.attributedPlaceHolder = iconString

tvMessage.layoutSubviews()

在swift 5。工作很好。

class BaseTextView: UITextView {

    // MARK: - Views
    private var placeholderLabel: UIlabel!

    // MARK: - Init
    override init(frame: CGRect, textContainer: NSTextContainer?) {
        super.init(frame: frame, textContainer: textContainer)
        setupUI()
        startupSetup()
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        setupUI()
        startupSetup()
    }

    deinit {
        NotificationCenter.default.removeObserver(self)
    }    
}

// MARK: - Setup UI
private extension BaseTextView {
    func setupUI() {
        addPlaceholderLabel()

        textColor = .textColor
    }

    func addPlaceholderLabel() {
        placeholderLabel = BaseLabel(frame: .zero)
        placeholderLabel.translatesAutoresizingMaskIntoConstraints = false
        insertSubview(placeholderLabel, at: 0)

        placeholderLabel.alpha = 0
        placeholderLabel.numberOfLines = 0
        placeholderLabel.backgroundColor = .clear
        placeholderLabel.textColor = .lightTextColor
        placeholderLabel.lineBreakMode = .byWordWrapping
        placeholderLabel.isUserInteractionEnabled = false
        placeholderLabel.font = UIFont.openSansSemibold.withSize(12)

        placeholderLabel.topAnchor.constraint(equalTo: topAnchor, constant: 8).isActive = true
        placeholderLabel.leftAnchor.constraint(equalTo: leftAnchor, constant: 5).isActive = true
        placeholderLabel.rightAnchor.constraint(lessThanOrEqualTo: rightAnchor, constant: -8).isActive = true
        placeholderLabel.bottomAnchor.constraint(lessThanOrEqualTo: bottomAnchor, constant: -8).isActive = true
    }
}

// MARK: - Startup
private extension BaseTextView {
    func startupSetup() {
        addObservers()
        textChanged(nil)
        font = UIFont.openSansSemibold.withSize(12)
    }    

    func addObservers() {
        NotificationCenter.default.addObserver(self, selector: #selector(textChanged(_:)), name: UITextView.textDidChangeNotification, object: nil)
    }
}

// MARK: - Actions
private extension BaseTextView {
    @objc func textChanged(_ sender: Notification?) {
        UIView.animate(withDuration: 0.2) {
            self.placeholderLabel.alpha = self.text.count == 0 ? 1 : 0
        }    
    }
}

// MARK: - Public methods
extension BaseTextView {
    public func setPlaceholder(_ placeholder: String) {
        placeholderLabel.text = placeholder
    }
}

在尝试了一些建议的方法后，我写了一个更清晰的实现，并将其发布到Github上。拉请求和问题是欢迎的。

与其他方法相比，这里提出了一些关键的改进:

不会在drawRect:中分配一个UILabel。(请不要这样做。) 不将文本视图的当前文本与所需的占位符进行比较以交换颜色。 当听写处于活动状态时隐藏占位符(如UITextField)。

TextView占位符

import UIKit

@IBDesignable
open class KMPlaceholderTextView: UITextView {

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

    public let placeholderLabel: UILabel = UILabel()

    private var placeholderLabelConstraints = [NSLayoutConstraint]()

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

    @IBInspectable open var placeholderColor: UIColor = KMPlaceholderTextView.Constants.defaultiOSPlaceholderColor {
        didSet {
            placeholderLabel.textColor = placeholderColor
        }
    }

    override open var font: UIFont! {
        didSet {
            if placeholderFont == nil {
                placeholderLabel.font = font
            }
        }
    }

    open var placeholderFont: UIFont? {
        didSet {
            let font = (placeholderFont != nil) ? placeholderFont : self.font
            placeholderLabel.font = font
        }
    }

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

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

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

    override open 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() {
        #if swift(>=4.2)
        let notificationName = UITextView.textDidChangeNotification
        #else
        let notificationName = NSNotification.Name.UITextView.textDidChangeNotification
        #endif

        NotificationCenter.default.addObserver(self,
                                               selector: #selector(textDidChange),
                                               name: notificationName,
                                               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
        self.layoutIfNeeded()
    }

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

    deinit {
        #if swift(>=4.2)
        let notificationName = UITextView.textDidChangeNotification
        #else
        let notificationName = NSNotification.Name.UITextView.textDidChangeNotification
        #endif

        NotificationCenter.default.removeObserver(self,
                                                  name: notificationName,
                                                  object: nil)
    }

}

使用

另一个解决方案

import UIKit

protocol PlaceholderTextViewDelegate: class {

    func placeholderTextViewDidChangeText(_ text: String)
    func placeholderTextViewDidEndEditing(_ text: String)
}

final class PlaceholderTextView: UITextView {

    weak var notifier: PlaceholderTextViewDelegate?
    var ignoreEnterAction: Bool = true

    var placeholder: String? {
        didSet {
            text = placeholder
            selectedRange = NSRange(location: 0, length: 0)
        }
    }

    var placeholderColor = UIColor.lightGray {
        didSet {
            if text == placeholder {
                textColor = placeholderColor
            }
        }
    }
    var normalTextColor = UIColor.lightGray

    var placeholderFont = UIFont.sfProRegular(28)

    fileprivate var placeholderLabel: UILabel?

    // MARK: - LifeCycle

    override var text: String? {
        didSet {
            if text == placeholder {
                textColor = placeholderColor
            } else {
                textColor = normalTextColor
            }
        }
    }

    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
    }
}

extension PlaceholderTextView: UITextViewDelegate {

    // MARK: - UITextViewDelegate
    func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {

        if text == "" && textView.text == placeholder {
            return false
        }

        if let placeholder = placeholder,
            textView.text == placeholder,
            range.location <= placeholder.count {
            textView.text = ""
        }

        if ignoreEnterAction && text == "\n" {
            textView.resignFirstResponder()
            return false
        }
        return true
    }

    func textViewDidChange(_ textView: UITextView) {
        if let placeholder = placeholder {
            textView.text = textView.text.replacingOccurrences(of: placeholder, with: "")
        }

        if let placeholder = placeholder,
            text?.isEmpty == true {
            text = placeholder
            textColor = placeholderColor

            selectedRange = NSRange(location: 0, length: 0)
        } else {
            textColor = normalTextColor
        }

        notifier?.placeholderTextViewDidChangeText(textView.text)
    }

    func textViewDidChangeSelection(_ textView: UITextView) {
        if let placeholder = placeholder,
            text == placeholder {
            selectedRange = NSRange(location: 0, length: 0)
        }
    }

    func textViewDidEndEditing(_ textView: UITextView) {
        notifier?.placeholderTextViewDidEndEditing(textView.text)

        if let placeholder = placeholder,
            text?.isEmpty == true {
            text = placeholder
            textColor = placeholderColor
            selectedRange = NSRange(location: 0, length: 0)
        } else {
            textColor = normalTextColor
        }
    }
}

结果:

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!