iOS开发-UITextView实现PlaceHolder的方式

之前开发遇到过UITextField中加入一个PlaceHolder的问题，直接设置一下即可，不过这次是需要在UITextView中实现一个PlaceHolder，跟之前有点不同。在网上参考了各位前辈的解决方案，大概有两种方式，第一种方式很猥琐，就是直接给UITextView的text赋值，比如说默认提示是"博客园FlyElephant"，在textViewDidChange中判断是不是“博客园FlyElephant”，如果是就清空，如果不是就继续提示，弊端就是用户输入的内容不能和你的默认提示一样，第二种方式需要加入一个UILabel，同样在textViewDidChange中进行判断，一般都是这么实现，不过有的都是创建textView中的时候创建UILabel，这样做无可厚非，不过最好还是抽象出来。继承UITextView扩展一下，新建一个FEPlaceHolderTextView：

头文件:

//

//  FEPlaceHolderTextView.h

//  MyTextViewDemo

//http://www.cnblogs.com/xiaofeixiang

//  Created by keso on 15/5/17.

//  Copyright (c) 2015年 keso. All rights reserved.

//

#import <UIKit/UIKit.h>

@interface FEPlaceHolderTextView : UITextView

@property (nonatomic, retain) NSString *placeholder;

@property (nonatomic, retain) UIColor *placeholderColor;

-(void)textChanged:(NSNotification*)notification;

@end

　实现文件:

//

//  FEPlaceHolderTextView.m

//  MyTextViewDemo

//http://www.cnblogs.com/xiaofeixiang

//  Created by keso on 15/5/17.

//  Copyright (c) 2015年 keso. All rights reserved.

//

#import "FEPlaceHolderTextView.h"

@interface FEPlaceHolderTextView ()

@property (nonatomic, retain) UILabel *placeHolderLabel;

@end

@implementation FEPlaceHolderTextView

CGFloat const UI_PLACEHOLDER_TEXT_CHANGED_ANIMATION_DURATION = 0.25;

- (void)dealloc

{

    [[NSNotificationCenter defaultCenter] removeObserver:self];

}

- (void)awakeFromNib

{

    [super awakeFromNib];

    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,10)];

            _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

　调用:

    self.textView=[[FEPlaceHolderTextView alloc]initWithFrame:CGRectMake(10, 30, CGRectGetWidth(self.view.frame)-20, 200)];

    self.textView.placeholder=@"博客园FlyElephant\n博客地址:http://www.cnblogs.com/xiaofeixiang";

    self.textView.layer.borderColor=[UIColor lightGrayColor].CGColor;

    self.textView.layer.borderWidth=1.0;

    self.textView.scrollEnabled = YES;

    self.textView.autoresizingMask =

    UIViewAutoresizingFlexibleHeight; //自适应高度

    self.textView.returnKeyType = UIReturnKeyDefault; //返回键的类型

    self.textView.keyboardType = UIKeyboardTypeDefault; //键盘类型

    [self.view addSubview:self.textView];

效果:

巴特西

iOS开发-UITextView实现PlaceHolder的方式

最新文章

热门文章