UITextView 和 UITextField 的提示信息placeholder

一、UITextFiled和UITextView很像，区别是前一个是只显示一行文本（即使打了回车，可只是显示一行），后一个可显示多行文本。两个的delegate方法也很像.

但是UITextFiled有一个属性placeholder,即文本框的提示信息。而UITextView则没有。一般当点击文本框的时候都需要将默认的提示信息去掉，将光标移动到开始位置。

 

但是对于UITextView则没有placeholder这个属性，可以直接设置textView.text = @"请您输入电话号码". 清除默认的text有几种方法

1.在UITextView上添加一个UILabel,再在-(void)textviewDidChanged:(UITextView*)textView方法中移除掉这个Label，[label  removeFromSuperView];

2.继承UITextView，在drawRect中添加或者删除placeholder:  参考http://stackoverflow.com/questions/1328638/placeholder-in-uitextview

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SSTextView.h   // //  SSTextView.h //  SSToolkit // //  Created by Sam Soffes on 8/18/10. //  Copyright 2010-2011 Sam Soffes. All rights reserved. //   /**  UITextView subclass that adds placeholder support like UITextField has.  */ @interface SSTextView : UITextView   /**  The string that is displayed when there is no other text in the text view.    The default value is `nil`.  */ @property (nonatomic, retain) NSString *placeholder;   /**  The color of the placeholder.    The default is `[UIColor lightGrayColor]`.  */ @property (nonatomic, retain) UIColor *placeholderColor;   @end   SSTextView.m   // //  SSTextView.m //  SSToolkit // //  Created by Sam Soffes on 8/18/10. //  Copyright 2010-2011 Sam Soffes. All rights reserved. //   #import "SSTextView.h"   @interface SSTextView () - (void)_initialize; - (void)_updateShouldDrawPlaceholder; - (void)_textChanged:(NSNotification *)notification; @end     @implementation SSTextView {     BOOL _shouldDrawPlaceholder; }     #pragma mark - Accessors   @synthesize placeholder = _placeholder; @synthesize placeholderColor = _placeholderColor;   - (void)setText:(NSString *)string {     [super setText:string];     [self _updateShouldDrawPlaceholder]; }     - (void)setPlaceholder:(NSString *)string {     if ([string isEqual:_placeholder]) {         return;     }       [_placeholder release];     _placeholder = [string retain];       [self _updateShouldDrawPlaceholder]; }     #pragma mark - NSObject   - (void)dealloc {     [[NSNotificationCenter defaultCenter] removeObserver:self name:UITextViewTextDidChangeNotification object:self];       [_placeholder release];     [_placeholderColor release];     [super dealloc]; }     #pragma mark - UIView   - (id)initWithCoder:(NSCoder *)aDecoder {     if ((self = [super initWithCoder:aDecoder])) {         [self _initialize];     }     return self; }     - (id)initWithFrame:(CGRect)frame {     if ((self = [super initWithFrame:frame])) {         [self _initialize];     }     return self; }     - (void)drawRect:(CGRect)rect {     [super drawRect:rect];       if (_shouldDrawPlaceholder) {         [_placeholderColor set];         [_placeholder drawInRect:CGRectMake(8.0f, 8.0f, self.frame.size.width - 16.0f, self.frame.size.height - 16.0f) withFont:self.font];     } }     #pragma mark - Private   - (void)_initialize {     [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(_textChanged:) name:UITextViewTextDidChangeNotification object:self];       self.placeholderColor = [UIColor colorWithWhite:0.702f alpha:1.0f];     _shouldDrawPlaceholder = NO; }     - (void)_updateShouldDrawPlaceholder {     BOOL prev = _shouldDrawPlaceholder;     _shouldDrawPlaceholder = self.placeholder && self.placeholderColor && self.text.length == 0;       if (prev != _shouldDrawPlaceholder) {         [self setNeedsDisplay];     } }     - (void)_textChanged:(NSNotification *)notificaiton {     [self _updateShouldDrawPlaceholder];    }   @end

 3.还是使用UITextView的delegate方法

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- (BOOL) textViewShouldBeginEditing:(UITextView *)textView {     if(textView.tag == 0) {         textView.text = @"";         textView.textColor = [UIColor blackColor];         textView.tag = 1;     }     return YES; } - (void)textViewDidChange:(UITextView *)textView {    if([textView.text length] == 0)    {        textView.text = @"Foobar placeholder";        textView.textColor = [UIColor lightGrayColor];        textView.tag = 0;    } }

 

二、如果希望一进入Controller页面,就显示键盘，可以在viewWillAppear或者viewDidAppear中 添加[textFiled becomeFirstResponser]