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
修改占位符文本颜色最简单的方法是通过XCode故事板接口构建器。选择感兴趣的UITextField并打开右侧的标识检查器。单击User Defined Runtime Attributes中的加号,并添加一个新行,其中Key Path为_placeholderLabel。输入颜色和值到你想要的颜色。
其他回答
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
我做了我自己版本的UITextView的子类。我喜欢Sam Soffes使用通知的想法,但我不喜欢drawRect: overwrite。对我来说太过分了。我认为我做了一个非常干净的实现。
你可以看看我的子类。还包括一个演示项目。
斯威夫特3.1
在尝试了所有快速的答案之后,这个答案将为我节省3个小时的研究时间。希望这能有所帮助。
确保你的textField(不管你有什么自定义名称)指向它在Storyboard中的委托,并且有一个@IBOutlet和你的customtextfield 将以下内容添加到viewDidLoad()中,加载视图时会出现:
告诉我什么看起来是占位符:
yourCustomTextField = "Start typing..."
yourCustomTextField.textColor = .lightGray
在viewDidLoad外部但在同一个类内部添加以下声明:UIViewController, UITextViewDelegate, UINavigationControllerDelegate
这段代码将使yourCustomTextField在输入textField时消失:
func textViewDidBeginEditing (_ textView: UITextView) {
if (textView.text == "Start typing...") {
textView.text = ""
textView.textColor = .black
}
textView.becomeFirstResponder()
}
func textViewDidEndEditing(_ textView: UITextView) {
if (textView.text == "") {
textView.text = "Start typing..."
textView.textColor = .lightGray
}
textView.resignFirstResponder()
}
Jason的答案在iOS7中看起来有点不对劲,通过调整_placeHolderLabel的偏移量来修复它:
- (void)drawRect:(CGRect)rect
{
if( [[self placeholder] length] > 0 )
{
if (_placeHolderLabel == nil )
{
if ([[UIDevice currentDevice].systemVersion floatValue] >= 7)
_placeHolderLabel = [[UILabel alloc] initWithFrame:CGRectMake(4,8,self.bounds.size.width - 8,0)];
else
_placeHolderLabel = [[UILabel alloc] initWithFrame:CGRectMake(8,8,self.bounds.size.width - 16,0)];
_placeHolderLabel.lineBreakMode = NSLineBreakByWordWrapping;
_placeHolderLabel.numberOfLines = 0;
_placeHolderLabel.font = self.font;
_placeHolderLabel.backgroundColor = [UIColor clearColor];
_placeHolderLabel.textColor = self.placeholderColor;
_placeHolderLabel.alpha = 0;
_placeHolderLabel.tag = 999;
[self addSubview:_placeHolderLabel];
}
_placeHolderLabel.text = self.placeholder;
[_placeHolderLabel sizeToFit];
[self sendSubviewToBack:_placeHolderLabel];
}
if( [[self text] length] == 0 && [[self placeholder] length] > 0 )
{
[[self viewWithTag:999] setAlpha:1];
}
[super drawRect:rect];
}
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
}
}