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
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);
}
}
其他回答
简单地创建UITextView的@IBDesignable子类:
@IBDesignable class AttributedTextView: UITextView {
private let placeholderLabel = UILabel()
@IBInspectable var placeholder: String = "" {
didSet {
setupPlaceholderLabelIfNeeded()
textViewDidChange()
}
}
override var text: String! {
didSet {
textViewDidChange()
}
}
//MARK: - Initialization
override func awakeFromNib() {
super.awakeFromNib()
setupPlaceholderLabelIfNeeded()
NotificationCenter.default.addObserver(self, selector: #selector(textViewDidChange), name: .UITextViewTextDidChange, object: nil)
}
//MARK: - Deinitialization
deinit {
NotificationCenter.default.removeObserver(self)
}
//MARK: - Internal
func textViewDidChange() {
placeholderLabel.isHidden = !text.isEmpty
layoutIfNeeded()
}
//MARK: - Private
private func setupPlaceholderLabelIfNeeded() {
placeholderLabel.removeFromSuperview()
placeholderLabel.frame = CGRect(x: 0, y: 8, width: frame.size.width, height: 0)
placeholderLabel.textColor = UIColor.lightGray
placeholderLabel.text = placeholder
placeholderLabel.sizeToFit()
insertSubview(placeholderLabel, at: 0)
}
}
然后在标识检查器中设置占位符:
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
我创建了一个实例变量来检查是否显示占位符:
BOOL showPlaceHolder;
UITextView * textView; // and also the textView
在viewDidLoad上设置:
[self setPlaceHolder];
下面是它的作用:
- (void)setPlaceholder
{
textView.text = NSLocalizedString(@"Type your question here", @"placeholder");
textView.textColor = [UIColor lightGrayColor];
self.showPlaceHolder = YES; //we save the state so it won't disappear in case you want to re-edit it
}
我还创建了一个按钮来退出键盘。您不必这样做,但这里很酷的事情是,如果没有输入任何内容,占位符将再次显示
- (void)textViewDidBeginEditing:(UITextView *)txtView
{
self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"Done" style:UIBarButtonItemStyleDone target:self action:@selector(resignKeyboard)];
if (self.showPlaceHolder == YES)
{
textView.textColor = [UIColor blackColor];
textView.text = @"";
self.showPlaceHolder = NO;
}
}
- (void)resignKeyboard
{
[textView resignFirstResponder];
//here if you created a button like I did to resign the keyboard, you should hide it
if (textView.text.length == 0) {
[self setPlaceholder];
}
}
I know there are already a lot of answers to this one, but I didn't really find any of them sufficient (at least in Swift). I needed the "placeholder" functionality of the UITextField in my UITextView (I wanted the exact behavior, including text display attributes, animations, etc, and didn't want to have to maintain this over time). I also wanted a solution that provided the same exact border as a UITextField (not an approximated one that looks sort of like it looks right now, but one that looks exactly like it and will always look exactly like it). So while I was not initially a fan of jamming an extra control into the mix, it seemed that in order to meet my goals I had to use an actual UITextField and let it do the work.
这个解决方案处理定位占位符和保持字体在两个控件之间的同步,以便占位符文本是输入到控件的文本的确切字体和位置(许多其他解决方案没有解决的问题)。
// This class is necessary to support "inset" (required to position placeholder
// appropriately in TextView)
//
class TextField: UITextField
{
var inset: UIEdgeInsets = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0);
override func textRectForBounds(bounds: CGRect) -> CGRect
{
return UIEdgeInsetsInsetRect(bounds, inset);
}
override func placeholderRectForBounds(bounds: CGRect) -> CGRect
{
return UIEdgeInsetsInsetRect(bounds, inset);
}
}
// This class implements a UITextView that has a UITextField behind it, where the
// UITextField provides the border and the placeholder text functionality (so that the
// TextView looks and works like a UITextField).
//
class TextView : UITextView, UITextViewDelegate
{
var textField = TextField();
required init?(coder: NSCoder)
{
super.init(coder: coder);
}
override init(frame: CGRect, textContainer: NSTextContainer?)
{
super.init(frame: frame, textContainer: textContainer);
self.delegate = self;
// Create a background TextField with clear (invisible) text and disabled
self.textField.borderStyle = UITextBorderStyle.RoundedRect;
self.textField.textColor = UIColor.clearColor();
self.textField.userInteractionEnabled = false;
// Align the background TextView to where text appears in the TextField, so
// that any placeholder will be in the correct position.
self.textField.contentVerticalAlignment = UIControlContentVerticalAlignment.Top;
self.textField.inset = UIEdgeInsets(
top: self.textContainerInset.top,
left: self.textContainerInset.left + self.textContainer.lineFragmentPadding,
bottom: self.textContainerInset.bottom,
right: self.textContainerInset.right
);
// The background TextField should use the same font (for the placeholder)
self.textField.font = self.font;
self.addSubview(textField);
self.sendSubviewToBack(textField);
}
convenience init()
{
self.init(frame: CGRectZero, textContainer: nil)
}
override var font: UIFont?
{
didSet
{
// Keep the font of the TextView and background textField in sync
self.textField.font = self.font;
}
}
var placeholder: String? = nil
{
didSet
{
self.textField.placeholder = self.placeholder;
}
}
override func layoutSubviews()
{
super.layoutSubviews()
// Do not scroll the background textView
self.textField.frame = CGRectMake(0, self.contentOffset.y, self.frame.width, self.frame.height);
}
// UITextViewDelegate - Note: If you replace delegate, your delegate must call this
func scrollViewDidScroll(scrollView: UIScrollView)
{
// Do not scroll the background textView
self.textField.frame = CGRectMake(0, self.contentOffset.y, self.frame.width, self.frame.height);
}
// UITextViewDelegate - Note: If you replace delegate, your delegate must call this
func textViewDidChange(textView: UITextView)
{
// Updating the text in the background textView will cause the placeholder to
// appear/disappear (including any animations of that behavior - since the
// textView is doing this itself).
self.textField.text = self.text;
}
}
这里有一个简单而聪明的方法来获得完美的行为。
让我们借用UITextField中的占位符。
Set up a textField and set its text transparent. self.placeholderTextField = [[UITextField alloc] init]; /* adjust the frame to fit it in the first line of your textView */ self.placeholderTextField.frame = CGRectMake(0.0, 0.0, yourTextView.width, 30.0); self.placeholderTextField.textColor = [UIColor clearColor]; self.placeholderTextField.userInteractionEnabled = NO; self.placeholderTextField.font = yourTextView.font; self.placeholderTextField.placeholder = @"sample placeholder"; [yourTextView addSubview:self.placeholderTextField]; Set textView's delegate and synchronize the textField and textView. yourTextView.delegate = self; then - (void)textViewDidChange:(UITextView *)textView { self.placeholderTextField.text = textView.text; } That's all.