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
我扩展了KmKndy的答案,这样在用户开始编辑UITextView之前,占位符仍然是可见的,而不仅仅是点击它。这反映了Twitter和Facebook应用程序的功能。我的解决方案不需要你子类和工作,如果用户类型直接或粘贴文本!
- (void)textViewDidChangeSelection:(UITextView *)textView{
if ([textView.text isEqualToString:@"What's happening?"] && [textView.textColor isEqual:[UIColor lightGrayColor]])[textView setSelectedRange:NSMakeRange(0, 0)];
}
- (void)textViewDidBeginEditing:(UITextView *)textView{
[textView setSelectedRange:NSMakeRange(0, 0)];
}
- (void)textViewDidChange:(UITextView *)textView
{
if (textView.text.length != 0 && [[textView.text substringFromIndex:1] isEqualToString:@"What's happening?"] && [textView.textColor isEqual:[UIColor lightGrayColor]]){
textView.text = [textView.text substringToIndex:1];
textView.textColor = [UIColor blackColor]; //optional
}
else if(textView.text.length == 0){
textView.text = @"What's happening?";
textView.textColor = [UIColor lightGrayColor];
[textView setSelectedRange:NSMakeRange(0, 0)];
}
}
- (void)textViewDidEndEditing:(UITextView *)textView
{
if ([textView.text isEqualToString:@""]) {
textView.text = @"What's happening?";
textView.textColor = [UIColor lightGrayColor]; //optional
}
[textView resignFirstResponder];
}
- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text{
if (textView.text.length > 1 && [textView.text isEqualToString:@"What's happening?"]) {
textView.text = @"";
textView.textColor = [UIColor blackColor];
}
return YES;
}
只需要记住在创建时使用准确的文本设置myUITextView即可。
UITextView *myUITextView = [[UITextView alloc] init];
myUITextView.delegate = self;
myUITextView.text = @"What's happening?";
myUITextView.textColor = [UIColor lightGrayColor]; //optional
在包含这些方法之前,让父类成为一个UITextView委托。
@interface MyClass () <UITextViewDelegate>
@end
其他回答
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。
我建议使用pod 'UITextView+Placeholder'
pod 'UITextView+Placeholder'
在代码中
#import "UITextView+Placeholder.h"
////
UITextView *textView = [[UITextView alloc] init];
textView.placeholder = @"How are you?";
textView.placeholderColor = [UIColor lightGrayColor];
在看完所有答案后,我意识到我需要一些简单的,同时可重用的东西,这样我就可以在我的项目中为所有uitextview添加相同的功能。最后我得到了以下代码:
extension UITextView {
// MARK: TextView PlaceHolderLabel Setup
func createPlaceHolderLabel(with text: String) {
let lbl = UILabel()
self.addSubview(lbl)
// Add your constraints here
lbl.text = text
lbl.textColor = .lightGray
}
// My Textview contains only one UILabel, and for my use case the below code works, tweak it according to your use case
// Lastly two methods to toggle between show and hide the placeholder label
func hidePlaceHolderLabel() {
guard let lbl = self.subviews.first(where: { $0 is UILabel }) else { return }
lbl.isHidden = true
}
func showPlaceHolderLabel() {
guard let lbl = self.subviews.first(where: { $0 is UILabel }) else { return }
lbl.isHidden = false
}
}
当UILabel作为子视图添加到UITextView时,textView游标位置和UILabel位置将不匹配,因此在占位符文本之前留下一个空间
class ViewController: UIViewController, UITextViewDelegate {
var textView: UITextView!
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(textView)
// Also setup textView constraints as per your need
// Add placeholder to your textView
// Leave one space before placeholder string
textView.createPlaceHolderLabel(with: " Address")
textView.delegate = self
}
然后在textViewdidChange方法中添加以下代码
func textViewDidChange(_ textView: UITextView) {
if textView.text.isEmpty {
textView.showPlaceHolderLabel()
} else {
textView.hidePlaceHolderLabel()
}
}
它可以在所有uitextview中重用。
我是这样做的:
UITextView2.h
#import <UIKit/UIKit.h>
@interface UITextView2 : UITextView <UITextViewDelegate> {
NSString *placeholder;
UIColor *placeholderColor;
}
@property(nonatomic, retain) NSString *placeholder;
@property(nonatomic, retain) UIColor *placeholderColor;
-(void)textChanged:(NSNotification*)notif;
@end
UITextView2.m
@implementation UITextView2
@synthesize placeholder, placeholderColor;
- (id)initWithFrame:(CGRect)frame {
if (self = [super initWithFrame:frame]) {
[self setPlaceholder:@""];
[self setPlaceholderColor:[UIColor lightGrayColor]];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textChanged:) name:UITextViewTextDidChangeNotification object:nil];
}
return self;
}
-(void)textChanged:(NSNotification*)notif {
if ([[self placeholder] length]==0)
return;
if ([[self text] length]==0) {
[[self viewWithTag:999] setAlpha:1];
} else {
[[self viewWithTag:999] setAlpha:0];
}
}
- (void)drawRect:(CGRect)rect {
if ([[self placeholder] length]>0) {
UILabel *l = [[UILabel alloc] initWithFrame:CGRectMake(8, 8, 0, 0)];
[l setFont:self.font];
[l setTextColor:self.placeholderColor];
[l setText:self.placeholder];
[l setAlpha:0];
[l setTag:999];
[self addSubview:l];
[l sizeToFit];
[self sendSubviewToBack:l];
[l release];
}
if ([[self text] length]==0 && [[self placeholder] length]>0) {
[[self viewWithTag:999] setAlpha:1];
}
[super drawRect:rect];
}
- (void)dealloc {
[[NSNotificationCenter defaultCenter] removeObserver:self];
[super dealloc];
}
@end
我对bcd的解决方案做了一些小修改,以允许从Xib文件初始化、文本包装和保持背景颜色。希望它能为其他人省去麻烦。
UIPlaceHolderTextView.h:
#import <Foundation/Foundation.h>
IB_DESIGNABLE
@interface UIPlaceHolderTextView : UITextView
@property (nonatomic, retain) IBInspectable NSString *placeholder;
@property (nonatomic, retain) IBInspectable UIColor *placeholderColor;
-(void)textChanged:(NSNotification*)notification;
@end
UIPlaceHolderTextView.m:
#import "UIPlaceHolderTextView.h"
@interface UIPlaceHolderTextView ()
@property (nonatomic, retain) UILabel *placeHolderLabel;
@end
@implementation UIPlaceHolderTextView
CGFloat const UI_PLACEHOLDER_TEXT_CHANGED_ANIMATION_DURATION = 0.25;
- (void)dealloc
{
[[NSNotificationCenter defaultCenter] removeObserver:self];
#if __has_feature(objc_arc)
#else
[_placeHolderLabel release]; _placeHolderLabel = nil;
[_placeholderColor release]; _placeholderColor = nil;
[_placeholder release]; _placeholder = nil;
[super dealloc];
#endif
}
- (void)awakeFromNib
{
[super awakeFromNib];
// Use Interface Builder User Defined Runtime Attributes to set
// placeholder and placeholderColor in Interface Builder.
if (!self.placeholder) {
[self setPlaceholder:@""];
}
if (!self.placeholderColor) {
[self setPlaceholderColor:[UIColor lightGrayColor]];
}
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textChanged:) name:UITextViewTextDidChangeNotification object:nil];
}
- (id)initWithFrame:(CGRect)frame
{
if( (self = [super initWithFrame:frame]) )
{
[self setPlaceholder:@""];
[self setPlaceholderColor:[UIColor lightGrayColor]];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textChanged:) name:UITextViewTextDidChangeNotification object:nil];
}
return self;
}
- (void)textChanged:(NSNotification *)notification
{
if([[self placeholder] length] == 0)
{
return;
}
[UIView animateWithDuration:UI_PLACEHOLDER_TEXT_CHANGED_ANIMATION_DURATION animations:^{
if([[self text] length] == 0)
{
[[self viewWithTag:999] setAlpha:1];
}
else
{
[[self viewWithTag:999] setAlpha:0];
}
}];
}
- (void)setText:(NSString *)text {
[super setText:text];
[self textChanged:nil];
}
- (void)drawRect:(CGRect)rect
{
if( [[self placeholder] length] > 0 )
{
if (_placeHolderLabel == nil )
{
_placeHolderLabel = [[UILabel alloc] initWithFrame:CGRectMake(8,8,self.bounds.size.width - 16,0)];
_placeHolderLabel.lineBreakMode = NSLineBreakByWordWrapping;
_placeHolderLabel.numberOfLines = 0;
_placeHolderLabel.font = self.font;
_placeHolderLabel.backgroundColor = [UIColor clearColor];
_placeHolderLabel.textColor = self.placeholderColor;
_placeHolderLabel.alpha = 0;
_placeHolderLabel.tag = 999;
[self addSubview:_placeHolderLabel];
}
_placeHolderLabel.text = self.placeholder;
[_placeHolderLabel sizeToFit];
[self sendSubviewToBack:_placeHolderLabel];
}
if( [[self text] length] == 0 && [[self placeholder] length] > 0 )
{
[[self viewWithTag:999] setAlpha:1];
}
[super drawRect:rect];
}
@end