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
简单的Swift 3解决方案
添加UITextViewDelegate到类中
设置你的textview .delegate = self
创建placeholderLabel和位置它在你的textview
现在动画placeholderLabel。alpha在textViewDidChange:
func textViewDidChange(_ textView: UITextView) {
let newAlpha: CGFloat = textView.text.isEmpty ? 1 : 0
if placeholderLabel.alpha != newAlpha {
UIView.animate(withDuration: 0.3) {
self.placeholderLabel.alpha = newAlpha
}
}
}
你可能不得不使用placeholderLabel位置来设置它,但这应该不会太难
其他回答
让我们简单点
创建一个UILabel并把它放在你的文本视图上(给文本作为占位符-设置颜色为灰色-你可以在你的xib中做这一切) 现在在头文件中声明UILabel和textviewDelegate 现在你可以简单地隐藏标签,当你点击textview
完整代码如下
头
@interface ViewController :UIViewController<UITextViewDelegate>{
}
@property (nonatomic,strong) IBOutlet UILabel *PlceHolder_label;
@property (nonatomic,strong) IBOutlet UITextView *TextView;
@end
实现
@implementation UploadFoodImageViewController
@synthesize PlceHolder_label,TextView;
- (void)viewDidLoad
{
[super viewDidLoad];
}
- (BOOL)textViewShouldBeginEditing:(UITextView *)textView{
if([textView isEqual:TextView]){
[PlceHolder_label setHidden:YES];
[self.tabScrlVw setContentOffset:CGPointMake(0,150) animated:YES];
}
return YES;
}
@end
别忘了连接textView和UILabel文件所有者从xib
我找到了自己的解决方案
- (void)textViewDidBeginEditing:(UITextView *)textView
{
if ([textView.text isEqualToString:PLACEHOLDER_TEXT])
{
textView.textColor = [UIColor lightGrayColor];
dispatch_async(dispatch_get_main_queue(), ^
{
textView.selectedRange = NSMakeRange(0, 0);
});
}
else
{
textView.textColor = [UIColor blackColor];
}
[textView becomeFirstResponder];
}
- (void)textViewDidEndEditing:(UITextView *)textView
{
if ([textView.text isEqualToString:@""])
{
textView.text = PLACEHOLDER_TEXT;
textView.textColor = [UIColor lightGrayColor];
}
[textView resignFirstResponder];
}
- (BOOL)textView:(UITextView *)textView
shouldChangeTextInRange:(NSRange)range
replacementText:(NSString *)text
{
if (range.location == 0 && range.length == [[textView text] length] && [text isEqualToString:@""])
{
textView.text = PLACEHOLDER_TEXT;
textView.textColor = [UIColor lightGrayColor];
dispatch_async(dispatch_get_main_queue(), ^
{
textView.selectedRange = NSMakeRange(0, 0);
});
return NO;
}
if ([textView.text isEqualToString:PLACEHOLDER_TEXT])
{
textView.text = @"";
textView.textColor = [UIColor blackColor];
}
return YES;
}
更简单,并且仍然考虑到用户在某些时候输入的一些文本
BOOL placeHolderTextVisible;
在viewDidLoad上,设置它为YES(或DidMoveToSuperview,或awakeFromNib)
然后,在 - (BOOL) textView:(UITextView*)textView shouldBeginEditing
- (BOOL)textViewShouldBeginEditing:(UITextView *)textView;
{
if (placeHolderTextVisible) {
placeHolderTextVisible = NO;
textView.text = @"";
}
return YES;
}
我已经创建了一个快速3版本的最高排名的答案
你只需要做UITextView的子类化。
import UIKit
class UIPlaceHolderTextView: UITextView {
//MARK: - Properties
@IBInspectable var placeholder: String?
@IBInspectable var placeholderColor: UIColor?
var placeholderLabel: UILabel?
//MARK: - Initializers
override func awakeFromNib() {
super.awakeFromNib()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
// Use Interface Builder User Defined Runtime Attributes to set
// placeholder and placeholderColor in Interface Builder.
if self.placeholder == nil {
self.placeholder = ""
}
if self.placeholderColor == nil {
self.placeholderColor = UIColor.black
}
NotificationCenter.default.addObserver(self, selector: #selector(textChanged(_:)), name: NSNotification.Name.UITextViewTextDidChange, object: nil)
}
func textChanged(_ notification: Notification) -> Void {
if self.placeholder?.count == 0 {
return
}
UIView.animate(withDuration: 0.25) {
if self.text.count == 0 {
self.viewWithTag(999)?.alpha = 1
}
else {
self.viewWithTag(999)?.alpha = 0
}
}
}
// Only override draw() if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
override func draw(_ rect: CGRect) {
super.draw(rect)
if (self.placeholder?.count ?? 0) > 0 {
if placeholderLabel == nil {
placeholderLabel = UILabel.init()
placeholderLabel?.lineBreakMode = .byWordWrapping
placeholderLabel?.numberOfLines = 0
placeholderLabel?.font = self.font
placeholderLabel?.backgroundColor = self.backgroundColor
placeholderLabel?.textColor = self.placeholderColor
placeholderLabel?.alpha = 0
placeholderLabel?.tag = 999
self.addSubview(placeholderLabel!)
placeholderLabel?.translatesAutoresizingMaskIntoConstraints = false
placeholderLabel?.topAnchor.constraint(equalTo: self.topAnchor, constant: 7).isActive = true
placeholderLabel?.leftAnchor.constraint(equalTo: self.leftAnchor, constant: 4).isActive = true
placeholderLabel?.bottomAnchor.constraint(equalTo: self.bottomAnchor).isActive = true
placeholderLabel?.rightAnchor.constraint(equalTo: self.rightAnchor).isActive = true
}
placeholderLabel?.text = self.placeholder
placeholderLabel?.sizeToFit()
self.sendSubview(toBack: self.placeholderLabel!)
}
if self.text.count == 0 && (self.placeholder?.count ?? 0) > 0 {
self.viewWithTag(999)?.alpha = 1
}
}
}
下面是“SAMTextView”ObjC代码的Swift端口,作为对这个问题的第一批回答之一。我在iOS 8上进行了测试。我调整了一些东西,包括占位符文本的位置的边界偏移,因为原来的位置太高,太右了(在那个帖子的一个评论中使用了建议)。
我知道有很多简单的解决方案,但我喜欢子类化UITextView的方法,因为它是可重用的,而且我不必在使用它的机制时使类变得混乱。
斯威夫特2.2:
import UIKit
class PlaceholderTextView: UITextView {
@IBInspectable var placeholderColor: UIColor = UIColor.lightGrayColor()
@IBInspectable var placeholderText: String = ""
override var font: UIFont? {
didSet {
setNeedsDisplay()
}
}
override var contentInset: UIEdgeInsets {
didSet {
setNeedsDisplay()
}
}
override var textAlignment: NSTextAlignment {
didSet {
setNeedsDisplay()
}
}
override var text: String? {
didSet {
setNeedsDisplay()
}
}
override var attributedText: NSAttributedString? {
didSet {
setNeedsDisplay()
}
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
setUp()
}
override init(frame: CGRect, textContainer: NSTextContainer?) {
super.init(frame: frame, textContainer: textContainer)
}
private func setUp() {
NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(PlaceholderTextView.textChanged(_:)),
name: UITextViewTextDidChangeNotification, object: self)
}
func textChanged(notification: NSNotification) {
setNeedsDisplay()
}
func placeholderRectForBounds(bounds: CGRect) -> CGRect {
var x = contentInset.left + 4.0
var y = contentInset.top + 9.0
let w = frame.size.width - contentInset.left - contentInset.right - 16.0
let h = frame.size.height - contentInset.top - contentInset.bottom - 16.0
if let style = self.typingAttributes[NSParagraphStyleAttributeName] as? NSParagraphStyle {
x += style.headIndent
y += style.firstLineHeadIndent
}
return CGRect(x: x, y: y, width: w, height: h)
}
override func drawRect(rect: CGRect) {
if text!.isEmpty && !placeholderText.isEmpty {
let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.alignment = textAlignment
let attributes: [ String: AnyObject ] = [
NSFontAttributeName : font!,
NSForegroundColorAttributeName : placeholderColor,
NSParagraphStyleAttributeName : paragraphStyle]
placeholderText.drawInRect(placeholderRectForBounds(bounds), withAttributes: attributes)
}
super.drawRect(rect)
}
}
斯威夫特4.2:
import UIKit
class PlaceholderTextView: UITextView {
@IBInspectable var placeholderColor: UIColor = UIColor.lightGray
@IBInspectable var placeholderText: String = ""
override var font: UIFont? {
didSet {
setNeedsDisplay()
}
}
override var contentInset: UIEdgeInsets {
didSet {
setNeedsDisplay()
}
}
override var textAlignment: NSTextAlignment {
didSet {
setNeedsDisplay()
}
}
override var text: String? {
didSet {
setNeedsDisplay()
}
}
override var attributedText: NSAttributedString? {
didSet {
setNeedsDisplay()
}
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
setUp()
}
override init(frame: CGRect, textContainer: NSTextContainer?) {
super.init(frame: frame, textContainer: textContainer)
}
private func setUp() {
NotificationCenter.default.addObserver(self,
selector: #selector(self.textChanged(notification:)),
name: Notification.Name("UITextViewTextDidChangeNotification"),
object: nil)
}
@objc func textChanged(notification: NSNotification) {
setNeedsDisplay()
}
func placeholderRectForBounds(bounds: CGRect) -> CGRect {
var x = contentInset.left + 4.0
var y = contentInset.top + 9.0
let w = frame.size.width - contentInset.left - contentInset.right - 16.0
let h = frame.size.height - contentInset.top - contentInset.bottom - 16.0
if let style = self.typingAttributes[NSAttributedString.Key.paragraphStyle] as? NSParagraphStyle {
x += style.headIndent
y += style.firstLineHeadIndent
}
return CGRect(x: x, y: y, width: w, height: h)
}
override func draw(_ rect: CGRect) {
if text!.isEmpty && !placeholderText.isEmpty {
let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.alignment = textAlignment
let attributes: [NSAttributedString.Key: Any] = [
NSAttributedString.Key(rawValue: NSAttributedString.Key.font.rawValue) : font!,
NSAttributedString.Key(rawValue: NSAttributedString.Key.foregroundColor.rawValue) : placeholderColor,
NSAttributedString.Key(rawValue: NSAttributedString.Key.paragraphStyle.rawValue) : paragraphStyle]
placeholderText.draw(in: placeholderRectForBounds(bounds: bounds), withAttributes: attributes)
}
super.draw(rect)
}
}