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
还有一个简单的答案,使用CATextLayer。
添加CATextLayer到UITextView的层。 使用UITextViewDelegate方法,简单地改变CATextLayer的颜色。
func txtViewPlaceholder() {
let textlayer = CATextLayer()
textlayer.frame = CGRect(x: 5, y: 5, width: 200, height: 18)
textlayer.contentsScale = UIScreen.main.scale
textlayer.fontSize = 12
textlayer.alignmentMode = kCAAlignmentLeft
textlayer.string = "Enter here"
textlayer.isWrapped = true
textlayer.name = "placeholder"
textlayer.backgroundColor = UIColor.white.cgColor
textlayer.foregroundColor = UIColor.black.cgColor
yourTxtVw.layer.insertSublayer(textlayer, at: 0)
}
func removeAddPlaceholder(remove: Bool, textView: UITextView) {
for layers in textView.layer.sublayers! where layers.name == "placeholder" {
if remove {
(layers as! CATextLayer).foregroundColor = UIColor.white.cgColor
} else {
(layers as! CATextLayer).foregroundColor = UIColor.black.cgColor
}
}
}
extension YourViewController : UITextViewDelegate {
func textViewShouldBeginEditing(_ textView: UITextView) -> Bool {
removeAddPlaceholder(remove: true, textView: textView)
return true
}
func textViewDidEndEditing(_ textView: UITextView) {
if textView.text.count <= 0 {
removeAddPlaceholder(remove: false, textView: textView)
}
}
}
你也可以创建一个新的类TextViewWithPlaceholder作为UITextView的子类。
(这段代码有点粗糙——但我认为它在正确的轨道上。)
@interface TextViewWithPlaceholder : UITextView
{
NSString *placeholderText; // make a property
UIColor *placeholderColor; // make a property
UIColor *normalTextColor; // cache text color here whenever you switch to the placeholderColor
}
- (void) setTextColor: (UIColor*) color
{
normalTextColor = color;
[super setTextColor: color];
}
- (void) updateForTextChange
{
if ([self.text length] == 0)
{
normalTextColor = self.textColor;
self.textColor = placeholderColor;
self.text = placeholderText;
}
else
{
self.textColor = normalTextColor;
}
}
在委托中,添加以下内容:
- (void)textViewDidChange:(UITextView *)textView
{
if ([textView respondsToSelector: @selector(updateForTextChange)])
{
[textView updateForTextChange];
}
}
嗨,你可以使用IQTextView可用的IQKeyboard管理器,这是简单的使用和集成只是设置类你的textview到IQTextView,你可以使用它的属性设置占位符标签与你想要的颜色。 您可以从IQKeyboardManager下载该库
或者你也可以从cocoapods上安装。
我刚刚发现,在iOS 10中,你现在可以将UITextView转换为方法的UITextField,并在方法中设置占位符。刚试过,它不需要子类化UITextView就能工作。
下面是一个对我有用的例子:
-(void)customizeTextField:(UITextField *)textField placeholder:(NSString *)pText withColor:(UIColor *)pTextColor{
textField.attributedPlaceholder = [[NSAttributedString alloc]
initWithString:pText
attributes:@{NSForegroundColorAttributeName:pTextColor}];
}
为了将它用于UITextView,你只需要将它传递给方法,使用像这样的类型转换:
[self customizeTextField:(UITextField*)_myTextView placeholder:@"Placeholder" withColor:[UIColor blackColor]];
注:经过测试,我发现这个解决方案在iOS9上也很好。但是会在iOS8.x上导致崩溃
我通读了所有这些,但提出了一个非常简短的Swift 3解决方案,在我的所有测试中都有效。它可以更一般化一点,但过程很简单。这是整个东西,我称之为“TextViewWithPlaceholder”。
import UIKit
class TextViewWithPlaceholder: UITextView {
public var placeholder: String?
public var placeholderColor = UIColor.lightGray
private var placeholderLabel: UILabel?
// Set up notification listener when created from a XIB or storyboard.
// You can also set up init() functions if you plan on creating
// these programmatically.
override func awakeFromNib() {
super.awakeFromNib()
NotificationCenter.default.addObserver(self,
selector: #selector(TextViewWithPlaceholder.textDidChangeHandler(notification:)),
name: .UITextViewTextDidChange,
object: self)
placeholderLabel = UILabel()
placeholderLabel?.alpha = 0.85
placeholderLabel?.textColor = placeholderColor
}
// By using layoutSubviews, you can size and position the placeholder
// more accurately. I chose to hard-code the size of the placeholder
// but you can combine this with other techniques shown in previous replies.
override func layoutSubviews() {
super.layoutSubviews()
placeholderLabel?.textColor = placeholderColor
placeholderLabel?.text = placeholder
placeholderLabel?.frame = CGRect(x: 6, y: 4, width: self.bounds.size.width-16, height: 24)
if text.isEmpty {
addSubview(placeholderLabel!)
bringSubview(toFront: placeholderLabel!)
} else {
placeholderLabel?.removeFromSuperview()
}
}
// Whenever the text changes, just trigger a new layout pass.
func textDidChangeHandler(notification: Notification) {
layoutSubviews()
}
}