如何在UITextView中添加占位符,类似于你可以为UITextField设置的占位符,在Swift中?
当前回答
我不知道为什么人们会把这个问题复杂化....这是相当直接和简单的。下面是UITextView的一个子类,它提供了所请求的功能。
- (void)customInit
{
self.contentMode = UIViewContentModeRedraw;
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textChanged:) name:UITextViewTextDidChangeNotification object:nil];
}
- (void)textChanged:(NSNotification *)notification
{
if (notification.object == self) {
if(self.textStorage.length != 0 || !self.textStorage.length) {
[self setNeedsDisplay];
}
}
}
#pragma mark - Setters
- (void)setPlaceholderText:(NSString *)placeholderText withFont:(UIFont *)font
{
self.placeholderText = placeholderText;
self.placeholderTextFont = font;
}
- (void)drawRect:(CGRect)rect
{
[super drawRect:rect];
[[UIColor lightGrayColor] setFill];
if (self.textStorage.length != 0) {
return;
}
CGRect inset = CGRectInset(rect, 8, 8);//Default rect insets for textView
NSDictionary *attributes = @{NSFontAttributeName: self.placeholderTextFont, NSForegroundColorAttributeName: [UIColor grayColor]};
[self.placeholderText drawInRect:inset withAttributes:attributes];
}`
其他回答
这是我准备使用的解决方案,如果您正在处理多个文本视图
func textViewShouldBeginEditing(textView: UITextView) -> Bool {
// Set cursor to the beginning if placeholder is set
if textView.textColor == UIColor.lightGrayColor() {
textView.selectedTextRange = textView.textRangeFromPosition(textView.beginningOfDocument, toPosition: textView.beginningOfDocument)
}
return true
}
func textView(textView: UITextView, shouldChangeTextInRange range: NSRange, replacementText text: String) -> Bool {
// Remove placeholder
if textView.textColor == UIColor.lightGrayColor() && text.characters.count > 0 {
textView.text = ""
textView.textColor = UIColor.blackColor()
}
if text == "\n" {
textView.resignFirstResponder()
return false
}
return true
}
func textViewDidChange(textView: UITextView) {
// Set placeholder if text is empty
if textView.text.isEmpty {
textView.text = NSLocalizedString("Hint", comment: "hint")
textView.textColor = UIColor.lightGrayColor()
textView.selectedTextRange = textView.textRangeFromPosition(textView.beginningOfDocument, toPosition: textView.beginningOfDocument)
}
}
func textViewDidChangeSelection(textView: UITextView) {
// Set cursor to the beginning if placeholder is set
let firstPosition = textView.textRangeFromPosition(textView.beginningOfDocument, toPosition: textView.beginningOfDocument)
// Do not change position recursively
if textView.textColor == UIColor.lightGrayColor() && textView.selectedTextRange != firstPosition {
textView.selectedTextRange = firstPosition
}
}
我们可以很容易地实现textview占位符,如果我们正在使用pod IQKeyboardManagerSwift在我们的项目中,只需遵循4个步骤
我们必须将类IQTextView分配给我们的TextView类。 我们必须在Controller页面中导入IQKeyboardManagerSwift 最后但并非最不重要的是,在控制器页面的textView的出口//如果你想:) 通过storyboard inspectable给textView一些占位符文本
迅速:
以编程方式或通过Interface Builder添加你的文本视图,如果是最后一个,创建outlet:
@IBOutlet weak var yourTextView: UITextView!
请添加委托(UITextViewDelegate):
class ViewController: UIViewController, UITextViewDelegate {
在viewDidLoad方法中,添加如下内容:
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
yourTextView.delegate = self
yourTextView.text = "Placeholder text goes right here..."
yourTextView.textColor = UIColor.lightGray
现在让我来介绍一下神奇的部分,添加这个函数:
func textViewDidBeginEditing(_ textView: UITextView) {
if yourTextView.textColor == UIColor.lightGray {
yourTextView.text = ""
yourTextView.textColor = UIColor.black
}
}
请注意,这将在编辑开始时执行,在那里我们将检查条件来告知状态,使用color属性。 设置文本为nil我不建议。在此之后,我们将文本颜色设置为所需的颜色,在本例中为黑色。
现在也添加这个函数:
func textViewDidEndEditing(_ textView: UITextView) {
if yourTextView.text == "" {
yourTextView.text = "Placeholder text ..."
yourTextView.textColor = UIColor.lightGray
}
}
让我坚持一下,不要与零进行比较,我已经试过了,它不会起作用。然后我们将值设置回占位符样式,并将颜色设置回占位符颜色,因为这是在textViewDidBeginEditing中检查的条件。
基于这里已经给出的一些很好的建议,我能够将以下轻量级的、与接口生成器兼容的UITextView子类组合在一起,它是:
包括可配置的占位符文本,样式就像UITextField一样。 不需要任何额外的子视图或约束。 不需要来自ViewController的任何委托或其他行为。 不需要任何通知。 保持占位符文本与查看字段文本属性的任何外部类完全分离。
任何改进建议都是受欢迎的,特别是如果有任何方法通过编程来获取iOS的占位符颜色,而不是硬编码它。
斯威夫特v5:
import UIKit
@IBDesignable class TextViewWithPlaceholder: UITextView {
override var text: String! { // Ensures that the placeholder text is never returned as the field's text
get {
if showingPlaceholder {
return "" // When showing the placeholder, there's no real text to return
} else { return super.text }
}
set { super.text = newValue }
}
@IBInspectable var placeholderText: String = ""
@IBInspectable var placeholderTextColor: UIColor = UIColor(red: 0.78, green: 0.78, blue: 0.80, alpha: 1.0) // Standard iOS placeholder color (#C7C7CD). See https://stackoverflow.com/questions/31057746/whats-the-default-color-for-placeholder-text-in-uitextfield
private var showingPlaceholder: Bool = true // Keeps track of whether the field is currently showing a placeholder
override func didMoveToWindow() {
super.didMoveToWindow()
if text.isEmpty {
showPlaceholderText() // Load up the placeholder text when first appearing, but not if coming back to a view where text was already entered
}
}
override func becomeFirstResponder() -> Bool {
// If the current text is the placeholder, remove it
if showingPlaceholder {
text = nil
textColor = nil // Put the text back to the default, unmodified color
showingPlaceholder = false
}
return super.becomeFirstResponder()
}
override func resignFirstResponder() -> Bool {
// If there's no text, put the placeholder back
if text.isEmpty {
showPlaceholderText()
}
return super.resignFirstResponder()
}
private func showPlaceholderText() {
showingPlaceholder = true
textColor = placeholderTextColor
text = placeholderText
}
}
import UIKit
import RxSwift
@IBDesignable class TextViewWithPlaceholder: UITextView {
//MARK: - Propertise
@IBInspectable var placeholderText: String = ""
let placeholderLabel = LocalizedUILabel()
private let hidePlaceholderObserver = PublishSubject<Bool>()
let disposeBag = DisposeBag()
//MARK: - Did Move To Window
override func didMoveToWindow() {
super.didMoveToWindow()
observeOnTextViewEditing()
configurePlaceholder()
}
//MARK: - Observe On Text View Editing
private func observeOnTextViewEditing() {
rx.text.subscribe(onNext: { [weak self] selectedText in
guard let self = self else { return }
self.hidePlaceholderObserver.onNext((selectedText?.isEmpty ?? true) ? false : true)
}).disposed(by: disposeBag)
}
//MARK: - Observe On Show Hide Placeholder
private func configurePlaceholder() {
hidePlaceholderObserver
.bind(to: placeholderLabel.rx.isHidden)
.disposed(by: disposeBag)
placeholderLabel.text = placeholderText
placeholderLabel.font = UIFont(name: "Poppins-Semibold", size: 16) ?? UIFont()
placeholderLabel.textColor = .lightGray
placeholderLabel.sizeToFit()
placeholderLabel.frame.origin = CGPoint(x: 8, y: 8)
addSubview(placeholderLabel)
}
}
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
- 如何舍入一个双到最近的Int在迅速?
- 扁平化数组的数组在Swift
- Swift:声明一个空字典
- 在成功提交我的应用程序后,“太多符号文件”
- 从数组中随机选择一个元素
- 首先添加一个UIView,甚至是导航栏
- 我如何改变UIButton标题颜色?
- 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
- CFNetwork SSLHandshake iOS 9失败
- swift语言中的结构与类