实现placeholder属性的UITextView

GGPlaceholderTextView简介

GGPlaceholderTextView

也是对

text

操作，具体逻辑如下：

继承

UITextView

，并设置

placeholder

属性

注册开始编辑和结束编辑通知，然后对

text

做相应的操作

通过

UIApplicationWillTerminateNotification

通知，在APP退出的时候移除通知。

我把

GGPlaceholderTextView

写在下面。不过，微信里看代码还是不太方便，我已经把代码push到:iOSStrongDemo。你可以下载下来。

GGPlaceholderTextView.h

#import <UIKit/UIKit.h>

@interface GGPlaceholderTextView : UITextView
@property(nonatomic, strong) NSString *placeholder;

@end

定义

placeholder

属性，类似于

UITextField

。

GGPlaceholderTextView.m

#import "GGPlaceholderTextView.h"

@implementation GGPlaceholderTextView

- (id)initWithFrame:(CGRect)frame {
if (self = [super initWithFrame:frame]) {
[self addObserver];
}
return self;
}

- (id)init {
if (self = [super init]) {
[self addObserver];
}
return self;
}

- (void)setPlaceholder:(NSString *)placeholder
{
_placeholder = placeholder;
self.text = placeholder;
self.textColor = [UIColor grayColor];
}

-(void)addObserver
{
//注册通知
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(didBeginEditing:) name:UITextViewTextDidBeginEditingNotification object:self];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(didEndEditing:) name:UITextViewTextDidEndEditingNotification object:self];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(terminate:) name:UIApplicationWillTerminateNotification object:[UIApplication sharedApplication]];
}

- (void)terminate:(NSNotification *)notification {
//移除通知
[[NSNotificationCenter defaultCenter] removeObserver:self];
}

- (void)didBeginEditing:(NSNotification *)notification {
if ([self.text isEqualToString:self.placeholder]) {
self.text = @"";
self.textColor = [UIColor blackColor];
}
}

- (void)didEndEditing:(NSNotification *)notification {
if (self.text.length<1) {
self.text = self.placeholder;
self.textColor = [UIColor grayColor];
}
}

@end

以上就是关于

GGPlaceholderTextView

的实现，如果你有类似需求，直接拿去用吧！具体用法请往下看。

实践

GGPlaceholderTextView *textView = [[GGPlaceholderTextView alloc] initWithFrame:CGRectMake(0, 64, SCREEN.width , 200)];
textView.backgroundColor = [UIColor whiteColor];
textView.placeholder = @"关注微信公众号iOS开发：iOSDevTip";
[self.view addSubview:textView];

经过封装后的

GGPlaceholderTextView

，使用起来是不是跟

UITextField

非常相似。当然，我封装的比较简单，github上也有一些朋友封装带

placeholder

属性的

UITextView

。比如：TextViewPlaceholder。感兴趣的童鞋可以去试用一下。