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
你可以在UITextView上设置标签
[UITextView addSubView:lblPlaceHoldaer];
并隐藏在TextViewdidChange方法上。
这是一个简单易行的方法。
其他回答
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;
}
如果有人需要Swift的解决方案:
添加UITextViewDelegate到类中
var placeHolderText = "Placeholder Text..."
override func viewDidLoad() {
super.viewDidLoad()
textView.delegate = self
}
func textViewShouldBeginEditing(textView: UITextView) -> Bool {
self.textView.textColor = .black
if(self.textView.text == placeHolderText) {
self.textView.text = ""
}
return true
}
func textViewDidEndEditing(textView: UITextView) {
if(textView.text == "") {
self.textView.text = placeHolderText
self.textView.textColor = .lightGray
}
}
override func viewWillAppear(animated: Bool) {
if(currentQuestion.answerDisplayValue == "") {
self.textView.text = placeHolderText
self.textView.textColor = .lightGray
} else {
self.textView.text = "xxx" // load default text / or stored
self.textView.textColor = .black
}
}
- (BOOL) textViewShouldBeginEditing:(UITextView *)textView
{
//NSLog(@"textViewShouldBeginEditing");
if( [tvComment.text isEqualToString:@"Comment"] && [tvComment.textColor isEqual:[UIColor lightGrayColor]] ){
tvComment.text = @"";
tvComment.textColor = [UIColor blackColor];
}
return YES;
}
- (void)keyboardWillBeHidden:(NSNotification*)aNotification{
//NSLog(@"keyboardWillBeHidden");
//Manage comment field placeholdertext
if(tvComment.text.length == 0){
tvComment.textColor = [UIColor lightGrayColor];
tvComment.text = @"Comment";
}
}
- (void)viewDidLoad
{
[super viewDidLoad];
tvComment.textColor = [UIColor lightGrayColor];
}
TVComment是包含问题中的textView的属性。这样就可以了。
我遵循了这个链接的代码。只有7个简单的步骤。它添加了一个UILabel的textView和隐藏/显示标签时,文本输入或从textView通过textView的textViewDidChangeSelection(_ textView: UITextView)委托方法。我将步骤放在代码上方的注释中。
// 1. make sure to include the UITextViewDelegate
class YourClass: UITextViewDelegate {
@IBOutlet weak var textView : UITextView!
// 2. create placeholder textLabel
let placeHolderTextLabel: UILabel = {
let placeholderLabel = UILabel()
placeholderLabel.text = "Placeholder text..."
placeholderLabel.sizeToFit()
placeholderLabel.textColor = UIColor.lightGray
return placeholderLabel
}()
override func viewDidLoad() {
super.viewDidLoad()
// 3. set textView delegate
textView.delegate = self
configurePlaceholderTextLabel()
}
func configurePlaceholderTextLabel() {
// 4. add placeholder label to textView, set it's frame and font
textView.addSubview(placeHolderTextLabel)
placeHolderTextLabel.frame.origin = CGPoint(x: 5, y: (textView.font?.pointSize)! / 2)
placeHolderTextLabel.font = UIFont.systemFont(ofSize: (textView.font?.pointSize)!)
// 5. decide wether the placeHolderTextLabel is hidden or not depending on if there is or isn't text inside the textView
placeHolderTextLabel.isHidden = !textView.text.isEmpty
}
// 6. implement textView delegate method to update the placeHolderTextLabel when the text is changed
func textViewDidChangeSelection(_ textView: UITextView) {
// 7. decide wether the placeHolderTextLabel is hidden or not depending on if there is or isn't text inside the textView when text in textView is changed
placeHolderTextLabel.isHidden = !textView.text.isEmpty
}
}
这是我的版本的UITextView与占位符支持。斯威夫特4.2 https://gist.github.com/hlung/c5dda3a0c2087e5ae6c1fce8822c4713
一个支持占位符文本的UITextView子类。它使用另一个 UILabel显示占位符,当文本为空时显示。