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()

你可以在UITextView上设置标签

[UITextView addSubView:lblPlaceHoldaer];

并隐藏在TextViewdidChange方法上。

这是一个简单易行的方法。

这里还有另一种方法，它复制了UITextField占位符的轻微缩进:

将UITextField拖到UITextView的右边，这样它们的左上角就对齐了。将占位符文本添加到文本字段。

在viewDidLoad中添加:

[tView setDelegate:self];
tView.contentInset = UIEdgeInsetsMake(-8,-8,0,0);
tView.backgroundColor = [UIColor clearColor];

然后添加:

- (void)textViewDidChange:(UITextView *)textView {
    if (textView.text.length == 0) {
        textView.backgroundColor = [UIColor clearColor];            
    } else {
        textView.backgroundColor = [UIColor whiteColor];
    }
}

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];
    }       
}

我是这样做的:

UITextView2.h

#import <UIKit/UIKit.h>

@interface UITextView2 : UITextView <UITextViewDelegate> {
 NSString *placeholder;
 UIColor *placeholderColor;
}

@property(nonatomic, retain) NSString *placeholder;
@property(nonatomic, retain) UIColor *placeholderColor;

-(void)textChanged:(NSNotification*)notif;

@end

UITextView2.m

@implementation UITextView2

@synthesize placeholder, placeholderColor;

- (id)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        [self setPlaceholder:@""];
        [self setPlaceholderColor:[UIColor lightGrayColor]];
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textChanged:) name:UITextViewTextDidChangeNotification object:nil];
    }
    return self;
}

-(void)textChanged:(NSNotification*)notif {
    if ([[self placeholder] length]==0)
        return;
    if ([[self text] length]==0) {
        [[self viewWithTag:999] setAlpha:1];
    } else {
        [[self viewWithTag:999] setAlpha:0];
    }

}

- (void)drawRect:(CGRect)rect {
    if ([[self placeholder] length]>0) {
        UILabel *l = [[UILabel alloc] initWithFrame:CGRectMake(8, 8, 0, 0)];
        [l setFont:self.font];
        [l setTextColor:self.placeholderColor];
        [l setText:self.placeholder];
        [l setAlpha:0];
        [l setTag:999];
        [self addSubview:l];
        [l sizeToFit];
        [self sendSubviewToBack:l];
        [l release];
    }
    if ([[self text] length]==0 && [[self placeholder] length]>0) {
        [[self viewWithTag:999] setAlpha:1];
    }
    [super drawRect:rect];
}

- (void)dealloc {
    [[NSNotificationCenter defaultCenter] removeObserver:self];
    [super dealloc];
}


@end

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
    }
}