iOS-UITextView的placeholder以及字数控制

曾经终败给现在 2023-10-18 22:51 105阅读 0赞

我们都知道UITextView控件不像UITextField一样有一个placeholder属性来设置文本输入框的灰色提示文本，这个时候我们可以自己来实现，效果图如下：

![20190803143907800.gif][]

代码如下：

static const int LimitMaxWord = 100;
    
    @interface AddRemarkView ()<UITextViewDelegate>
    
    /// 备注输入框
    @property (nonatomic, weak) UITextView *txvRemark;
    /// 备注placholder
    @property (nonatomic, weak) UILabel *lblPlaceHolder;
    /// 备注字数限制
    @property (nonatomic, weak) UILabel *lblCount;
    
    @end
    
    @implementation AddRemarkView
    
    - (instancetype)init {
        if (self == [super init]) {
            [self setSubView];
        }
        return self;
    }
    
    - (void) setSubView {
        self.backgroundColor = DefaultGrayCOLOR;
    
        /// 备注输入框
        UITextView *txvRemark = [[UITextView alloc]init];
        self.txvRemark = txvRemark;
        txvRemark.returnKeyType = UIReturnKeyDone;
        /// textview内
        txvRemark.textContainerInset = UIEdgeInsetsMake(12, 12, 25, 16);
        txvRemark.delegate = self;
        txvRemark.backgroundColor = [UIColor whiteColor];
        txvRemark.textColor = TextBlackCOLOR;
        txvRemark.font = SET_FONT(15);
        [self addSubview:txvRemark];
        [txvRemark mas_makeConstraints:^(MASConstraintMaker *make) {
            make.left.right.mas_equalTo(0);
            make.top.mas_equalTo(4);
            make.height.mas_equalTo(150);
        }];
        
        /// 备注placholder
        UILabel *lblPlaceHolder = [[UILabel alloc]init];
        self.lblPlaceHolder = lblPlaceHolder;
        lblPlaceHolder.text = BZLocalizedString(@"customer_remark_plachoder", nil);
        lblPlaceHolder.textColor = TextLightGrayCOLOR;
        lblPlaceHolder.font = SET_FONT(15);
        [self addSubview:lblPlaceHolder];
        [lblPlaceHolder mas_makeConstraints:^(MASConstraintMaker *make) {
            make.left.mas_equalTo(16);
            make.right.mas_equalTo(-16);
            make.top.equalTo(txvRemark.mas_top).offset(12);
            make.height.mas_equalTo(20);
        }];
        
        /// 备注字数限制(UITextView上添加不了view？？？)
        UILabel *lblCount = [[UILabel alloc]init];
        self.lblCount = lblCount;
        lblCount.textAlignment = NSTextAlignmentRight;
        lblCount.text = @"0/100";
        lblCount.textColor = TextLightGrayCOLOR;
        lblCount.font = SET_FONT(12);
        [self addSubview:lblCount];
        [lblCount mas_makeConstraints:^(MASConstraintMaker *make) {
            make.right.equalTo(txvRemark.mas_right).offset(-16);
            make.width.mas_equalTo(60);
            make.bottom.equalTo(txvRemark.mas_bottom).offset(-5);
            make.height.mas_equalTo(20);
        }];
        
        /// 保存
        UIButton *btnSave = [UIButton buttonWithType:UIButtonTypeCustom];
        btnSave.backgroundColor = MainThemeColor;
        btnSave.layer.masksToBounds = YES;
        btnSave.layer.cornerRadius = 2.0;
        [btnSave setTitle:BZLocalizedString(@"common_save", nil) forState:UIControlStateNormal];
        [btnSave setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
        btnSave.titleLabel.font = SET_FONT(15);
        [self addSubview:btnSave];
        [btnSave mas_makeConstraints:^(MASConstraintMaker *make) {
            make.left.mas_equalTo(16);
            make.right.mas_equalTo(-16);
            make.top.equalTo(txvRemark.mas_bottom).offset(50);
            make.height.mas_equalTo(@48);
        }];
        [btnSave addTarget:self
                    action:@selector(saveAction)
          forControlEvents:UIControlEventTouchUpInside];
    }
    
    #pragma mark - UITextViewDelegate
    - (void)textViewDidChange:(UITextView *)textView {
        self.lblPlaceHolder.hidden = YES;
        
        if (textView.text.length > LimitMaxWord) {
            textView.text = [textView.text substringToIndex:LimitMaxWord];
        }
        /// 取消按钮点击权限，并显示提示文字
        if (textView.text.length == 0) {
            self.lblPlaceHolder.hidden = NO;
        }
        
        /// 记录输入的字数，你若不统计字数，忽略这行
        self.lblCount.text = [NSString stringWithFormat:@"%lu/%d", (unsigned long)[textView.text length], LimitMaxWord];
    }
    
    - (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text {
        if([text isEqualToString:@"\n"]) {
            /// 判断输入的字是否是回车，即按下return
            /// 在这里做你响应return键的代码
            [textView resignFirstResponder];
            /// 这里返回NO，就代表return键值失效，即页面上按下return，不会出现换行，如果为yes，则输入页面会换行
            return NO;
        }
        NSString *str = [NSString stringWithFormat:@"%@%@", textView.text, text];
        if (str.length > LimitMaxWord){
            NSRange rangeIndex = [str rangeOfComposedCharacterSequenceAtIndex:LimitMaxWord];
            
            /// 字数超限
            if (rangeIndex.length == 1) {
                textView.text = [str substringToIndex:LimitMaxWord];
                /// 这里重新统计下字数，字数超限，我发现就不走textViewDidChange方法了，你若不统计字数，忽略这行
                self.lblCount.text = [NSString stringWithFormat:@"%lu/%d", (unsigned long)textView.text.length, LimitMaxWord];
            }else{
                NSRange rangeRange = [str rangeOfComposedCharacterSequencesForRange:NSMakeRange(0, LimitMaxWord)];
                textView.text = [str substringWithRange:rangeRange];
            }
            return NO;
        }
        return YES;
    }
    
    #pragma mark - Action
    - (void)saveAction {
        /// "customer_remark_plachoder" = "请输入备注信息，最多可输入100字。";
        /// "customer_remark_plachoderalert" = "请输入备注信息";
        [self.txvRemark resignFirstResponder];
        if(![self.txvRemark.text isEqualToString:BZLocalizedString(@"customer_remark_plachoder", nil)] &&
           self.txvRemark.text.length != 0){
            if ([self.delegate respondsToSelector:@selector(addRemarkWithAddRemarkView:withRemarkStr:)]) {
                [self.delegate addRemarkWithAddRemarkView:self
                                            withRemarkStr:self.txvRemark.text];
            }
        }else{
            [BZAlertView showAlterWillDismiss:BZLocalizedString(@"customer_remark_plachoderalert", nil)];
        }
    }
    
    @end

1、要实现UITextView的placeholder功能主要是在UITextView上添加一个UILabel，当键盘弹起或者开始输入文字的时候，将此UILabel隐藏掉即可，当文字长度= 0，此UILabel又显示

2、输入文本限制，到了一定长度不让输入，这里没有针对中英文，特殊符号进行占位符区分，大家可以候补一下

这里博主遇到一个问题，就是在UITextView上添加UILabel发现图层上没有显示，大家遇到可以帮忙解释一下，感激不尽！

[20190803143907800.gif]: https://img-blog.csdnimg.cn/20190803143907800.gif