iOS 프로그래밍 팁 - 7 UIPlaceHolderTextView

UITextField 는 placeholder 프로퍼티가 존재한다.
입력전에 grayColor로 보여주다가 입력이 시작되면 사라지는 것이다.

근데 멀티라인을 입력 할수 있는 UITextView는 이러한 placeholder프로퍼티가 없다.

UITextView 를 상속 받고 NSString *placeholder, 와 UIColor *placeholderColor 를
가지고 있는 UIPlaceHolderTextView를 만들어 사용할수 있다.

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)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 = 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

참고 : http://stackoverflow.com/questions/1328638/placeholder-in-uitextview