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
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
其他回答
你能做的是在文本属性中设置文本视图的初始值，并将textColor更改为[UIColor grayColor]或类似的东西。然后，每当文本视图变为可编辑时，清除文本并显示游标，如果文本字段再次为空，则将占位符文本放回。根据需要将颜色更改为[UIColor blackColor]。
它与UITextField中的占位符功能不完全相同，但很接近。
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
}
}
}
这里有一个更简单的解决方案，它的行为完全像UITextField的占位符，但不需要绘制自定义视图，或辞职第一响应器。
- (void) textViewDidChange:(UITextView *)textView{
if (textView.text.length == 0){
textView.textColor = [UIColor lightGrayColor];
textView.text = placeholderText;
[textView setSelectedRange:NSMakeRange(0, 0)];
isPlaceholder = YES;
} else if (isPlaceholder && ![textView.text isEqualToString:placeholderText]) {
textView.text = [textView.text substringToIndex:1];
textView.textColor = [UIColor blackColor];
isPlaceholder = NO;
}
}
(else if语句中的第二个检查是针对没有输入任何内容且用户按下退格键的情况)
只需要将你的类设置为UITextViewDelegate。在viewDidLoad中，你应该这样初始化
- (void) viewDidLoad{
// initialize placeholder text
placeholderText = @"some placeholder";
isPlaceholder = YES;
self.someTextView.text = placeholderText;
self.someTextView.textColor = [UIColor lightGrayColor];
[self.someTextView setSelectedRange:NSMakeRange(0, 0)];
// assign UITextViewDelegate
self.someTextView.delegate = self;
}
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:
推荐文章
- 如何删除默认的导航栏空间在SwiftUI导航视图
- 如何在iOS中使用Swift编程segue
- Swift -整数转换为小时/分钟/秒
- Swift:声明一个空字典
- 为什么ARC仍然需要@autoreleasepool ?
- 在成功提交我的应用程序后，“太多符号文件”
- 首先添加一个UIView，甚至是导航栏
- 我如何改变UIButton标题颜色?
- 如何从UIImage (Cocoa Touch)或CGImage (Core Graphics)获取像素数据?
- 在Swift中如何调用GCD主线程上的参数方法?
- NSLayoutConstraints是可动画的吗?
- iOS -构建失败，CocoaPods无法找到头文件
- Xcode 4挂在“附加到(应用程序名称)”
- CFNetwork SSLHandshake iOS 9失败
- 请求失败:不可接受的内容类型:文本/html使用AFNetworking 2.0
