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
在swift 5。工作很好。
class BaseTextView: UITextView {
// MARK: - Views
private var placeholderLabel: UIlabel!
// MARK: - Init
override init(frame: CGRect, textContainer: NSTextContainer?) {
super.init(frame: frame, textContainer: textContainer)
setupUI()
startupSetup()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
setupUI()
startupSetup()
}
deinit {
NotificationCenter.default.removeObserver(self)
}
}
// MARK: - Setup UI
private extension BaseTextView {
func setupUI() {
addPlaceholderLabel()
textColor = .textColor
}
func addPlaceholderLabel() {
placeholderLabel = BaseLabel(frame: .zero)
placeholderLabel.translatesAutoresizingMaskIntoConstraints = false
insertSubview(placeholderLabel, at: 0)
placeholderLabel.alpha = 0
placeholderLabel.numberOfLines = 0
placeholderLabel.backgroundColor = .clear
placeholderLabel.textColor = .lightTextColor
placeholderLabel.lineBreakMode = .byWordWrapping
placeholderLabel.isUserInteractionEnabled = false
placeholderLabel.font = UIFont.openSansSemibold.withSize(12)
placeholderLabel.topAnchor.constraint(equalTo: topAnchor, constant: 8).isActive = true
placeholderLabel.leftAnchor.constraint(equalTo: leftAnchor, constant: 5).isActive = true
placeholderLabel.rightAnchor.constraint(lessThanOrEqualTo: rightAnchor, constant: -8).isActive = true
placeholderLabel.bottomAnchor.constraint(lessThanOrEqualTo: bottomAnchor, constant: -8).isActive = true
}
}
// MARK: - Startup
private extension BaseTextView {
func startupSetup() {
addObservers()
textChanged(nil)
font = UIFont.openSansSemibold.withSize(12)
}
func addObservers() {
NotificationCenter.default.addObserver(self, selector: #selector(textChanged(_:)), name: UITextView.textDidChangeNotification, object: nil)
}
}
// MARK: - Actions
private extension BaseTextView {
@objc func textChanged(_ sender: Notification?) {
UIView.animate(withDuration: 0.2) {
self.placeholderLabel.alpha = self.text.count == 0 ? 1 : 0
}
}
}
// MARK: - Public methods
extension BaseTextView {
public func setPlaceholder(_ placeholder: String) {
placeholderLabel.text = placeholder
}
}
其他回答
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。
抱歉添加了另一个答案,但我只是拉出了这样的东西,这创建了最接近uitextfield的占位符。
希望这能帮助到一些人。
-(void)textViewDidChange:(UITextView *)textView{
if(textView.textColor == [UIColor lightGrayColor]){
textView.textColor = [UIColor blackColor]; // look at the comment section in this answer
textView.text = [textView.text substringToIndex: 0];// look at the comment section in this answer
}else if(textView.text.length == 0){
textView.text = @"This is some placeholder text.";
textView.textColor = [UIColor lightGrayColor];
textView.selectedRange = NSMakeRange(0, 0);
}
}
-(void)textViewDidChangeSelection:(UITextView *)textView{
if(textView.textColor == [UIColor lightGrayColor] && (textView.selectedRange.location != 0 || textView.selectedRange.length != 0)){
textView.selectedRange = NSMakeRange(0, 0);
}
}
- (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。
- (void)textViewDidChange:(UITextView *)textView
{
placeholderLabel.hidden = YES;
}
在textview上放一个标签。
这里还有另一种方法,它复制了UITextField占位符的轻微缩进:
将UITextField拖到UITextView的右边,这样它们的左上角就对齐了。将占位符文本添加到文本字段。
在viewDidLoad中添加:
[tView setDelegate:self];
tView.contentInset = UIEdgeInsetsMake(-8,-8,0,0);
tView.backgroundColor = [UIColor clearColor];
然后添加:
- (void)textViewDidChange:(UITextView *)textView {
if (textView.text.length == 0) {
textView.backgroundColor = [UIColor clearColor];
} else {
textView.backgroundColor = [UIColor whiteColor];
}
}