效果图:

h文件

@interface YLTextView : UITextView
@property (copy ,nonatomic)NSString *placeHoder;
@property (assign,nonatomic)BOOL hidePlaceHoder; //是否对placeHoder进行隐藏
@end

m 文件

//
//  YLTextView.m
//  YangLand
//
//  Created by 赵大财 on 16/3/13.
//  Copyright © 2016年 tshiny. All rights reserved.
//#import "YLTextView.h"@interface YLTextView ()@property (weak ,nonatomic)UILabel *placeHoderLabel;@end@implementation YLTextView- (instancetype)initWithFrame:(CGRect)frame {if (self = [super initWithFrame:frame]) {self.font = [UIFont systemFontOfSize:13];}return self;
}-(void)setFont:(UIFont *)font {[super setFont:font];self.placeHoderLabel.font = font;[self.placeHoderLabel sizeToFit]; //文字的大小 就是label的尺寸
}-(void)setPlaceHoder:(NSString *)placeHoder {_placeHoder = placeHoder;self.placeHoderLabel.text = placeHoder;[self.placeHoderLabel sizeToFit];
}- (void)setHidePlaceHoder:(BOOL)hidePlaceHoder {_hidePlaceHoder = hidePlaceHoder;self.placeHoderLabel.hidden = hidePlaceHoder;
}- (UILabel *)placeHoderLabel {if (!_placeHoderLabel) {UILabel *placeHoderLabel = [[UILabel alloc]init];[self addSubview:placeHoderLabel];_placeHoderLabel = placeHoderLabel;}return _placeHoderLabel;
}- (void)layoutSubviews {[super layoutSubviews];self.placeHoderLabel.x = 10;self.placeHoderLabel.y = 10;
}@end

控制器的使用

  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textChange) name:UITextViewTextDidChangeNotification object:nil]; //监听文字改变//文字改变方法
- (void)textChange {if (self.textView.text.length) {_textView.hidePlaceHoder = YES;}else {_textView.hidePlaceHoder = NO;}
}- (YLTextView *)textView {if (!_textView) {_textView = [[YLTextView alloc]initWithFrame:self.view.bounds];_textView.delegate = self;_textView.alwaysBounceVertical = YES; //这是让textView可上下滑动_textView.placeHoder = @"请发表今天的心情...";_textView.font = [UIFont systemFontOfSize:20];}return _textView;
}