我们都知道iOS开发中的UITextField有个placeholder属性，placeholder可以很方便引导用户输入。但是UITextView却没有placeholder属性。
一、猥琐的方法
如何让UITextView也有placeholder功能呢？今天给各位分享一个比较猥琐的做法。思路大概是这样的：
实现方法：
1.创建UITextView：
二、通常的方法
接下来来看比较通常的方法，哈哈~那么，这一次我将简单的封装一个UITextView。暂且取名叫GGPlaceholderTextView，GG前缀看着有点任性的哈。
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。
#import <UIKit/UIKit.h>
@interface GGPlaceholderTextView : UITextView
@property(nonatomic, strong) NSString *placeholder;
@end
#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
实践：
GGPlaceholderTextView *textView = [[GGPlaceholderTextView alloc] initWithFrame:CGRectMake(0, 64, SCREEN.width , 200)];
textView.backgroundColor = [UIColor whiteColor];
textView.placeholder = @"phpstudy.net";
[self.view addSubview:textView];