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
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:
其他回答
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];
}
我用swift写了一个类。您可以在需要时导入这个类。
import UIKit
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)
}
}
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
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:
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