带有placeholder的UITextView

 

• UIPlaceHolderTextView.h

#import <Foundation/Foundation.h>  @interface UIPlaceHolderTextView : UITextView {     NSString *placeholder;     UIColor *placeholderColor;  @private     UILabel *placeHolderLabel; }  @property (nonatomic, retain) UILabel *placeHolderLabel; @property (nonatomic, retain) NSString *placeholder; @property (nonatomic, retain) UIColor *placeholderColor;  -(void)textChanged:(NSNotification*)notification;  @end  

   
   
   
   

    
    
    
    
UIPlaceHolderTextView.m
   
   
   
   
#import "UIPlaceHolderTextView.h"  @implementation UIPlaceHolderTextView  @synthesize placeHolderLabel; @synthesize placeholder; @synthesize placeholderColor;  - (void)dealloc {     [[NSNotificationCenter defaultCenter] removeObserver:self];     [placeHolderLabel release]; placeHolderLabel = nil;     [placeholderColor release]; placeholderColor = nil;     [placeholder release]; placeholder = nil;     [super dealloc]; }  - (void)awakeFromNib {     [super awakeFromNib];     [self setPlaceholder:@""];     [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;     }      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 )     {         if ( placeHolderLabel == nil )         {             placeHolderLabel = [[UILabel alloc] initWithFrame:CGRectMake(8,8,self.bounds.size.width - 16,0)];             placeHolderLabel.lineBreakMode = UILineBreakModeWordWrap;             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