iOS 自定义TextView设置placeholder属性

用惯TextField的placeholder属性,当然在使用TextView自然而然 .placeholder可这时怎么点都点不出来,

下面废话不多说,直接介绍可以使用TextView. placeholder的方法

创建自定义placeHolderTextView类继承于UITextView

1. 在placeHolderTextView.h 中

#import <UIKit/UIKit.h>
@interface placeHolderTextView : UITextView
@property (nonatomic, retain) NSString *placeholder;
@property (nonatomic, retain) UIColor *placeholderColor;
-(void)textChanged:(NSNotification*)notification;
@end

2. 在placeHolderTextView.m中

 #import "placeHolderTextView.h"
@interface placeHolderTextView ()
@property (nonatomic, retain) UILabel *placeHolderLabel;
@end

@implementation placeHolderTextView
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-5,10)];
            _placeHolderLabel.lineBreakMode = NSLineBreakByWordWrapping;
            _placeHolderLabel.numberOfLines =0;
//            _placeHolderLabel.font = self.font; //调整textView字体
            _placeHolderLabel.font = [UIFont systemFontOfSize:14];
            _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

3. 使用步骤
   一. 导入头文件 #import "placeHolderTextView.h"

二. 定义属性

@property(strong,nonatomic) placeHolderTextView *textView;

三. 创建设置添加图层容器

    self.textView=[[cnhbPlaceHolderTextView alloc]initWithFrame:CGRectMake(10, 10, SCREEN_W-20, 110)];
    self.textView.placeholder=@" 描述 xxxxxxxxxxxxxxxx 信息";
    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];

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