对输入的数字4位加一个空格

在APP中，注册输入手机号、输入银行卡进行绑卡的操作是很常见的。下面介绍我的对输入框输入数字进行4位加一个空格的方法

思路

1. 有3种情况需要处理【1. 键盘输入时 2.粘贴 3.KVO监听到赋值 】
2. 因为多个页面会使用到这个功能，自己需要抽取方法；
3. 设置textfield的代理，在代理方法里面让textField调用抽取方法进行格式化

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string

3. KVO监听textField的text变化，在手动设置textField.text时，手动调用上述代理方法实现格式化
4. 通常在用户输入text或者设置text后需要执行自己的业务逻辑，此时通过block回调的方式解决

具体实现

1. 新建UITextField分类，抽取方法放在此分类下

/** 将输入框内用户输入的文字进行4位1空格格式化
 */
- (BOOL)bankCardFormatWithInputRange:(NSRange)range replacementString:(NSString *)string successInput:(void (^)())successInputBlock{
    // 每次输入了4位之后,如果此时是正在输入,则自动增加空格,如果正在删除,则自动删除空格!!!
    NSCharacterSet *characterSet = [NSCharacterSet characterSetWithCharactersInString:@"0123456789\b"];// "\b"=退格
    // 先判断准备添加\替换的字符是不是合法
    string = [string stringByReplacingOccurrencesOfString:@" " withString:@""];
    if ([string rangeOfCharacterFromSet:[characterSet invertedSet]].location != NSNotFound) {// 找到了非法字符
        return NO;
    }
    NSString *text = self.text;
    text = [text stringByReplacingCharactersInRange:range withString:string];
    text = [text stringByReplacingOccurrencesOfString:@" " withString:@""];
    
    NSString *newString = @"";
    while (text.length > 0) {
        
        NSString *subString = [text substringToIndex:MIN(text.length, 4)];
        newString = [newString stringByAppendingString:subString];
        if (subString.length == 4) {
            newString = [newString stringByAppendingString:@" "];
        }
        text = [text substringFromIndex:MIN(text.length, 4)];
    }
    
    newString = [newString stringByTrimmingCharactersInSet:[characterSet invertedSet]];// 这一步把首尾两端不合规矩的字符去除掉
    
    if (newString.length > 24) {
        newString = [newString substringWithRange:NSMakeRange(0, 24)];
    }
    self.text = newString;
    
    successInputBlock();
    return NO;
}

/** 将输入框内用户输入的文字手机号码格式化 xxx xxxx xxxx
 */
- (BOOL)phoneNumberFormatWithInputRange:(NSRange)range replacementString:(NSString *)string successInput:(void (^)())successInputBlock{
    
    /**1.当到第四位或第九位时,如果此时是正在输入,则自动增加空格,如果正在删除,则自动删除空格!!!
     *2.当到第13位时,截取前面的13位字符串,
     *3.若想要获取输入的手机,需要先删除空格;
     */
    
    NSCharacterSet *characterSet = [NSCharacterSet characterSetWithCharactersInString:@"0123456789\b"];// "\b"=退格
    // 先判断准备添加\替换的字符是不是合法
    string = [string stringByReplacingOccurrencesOfString:@" " withString:@""];
    if ([string rangeOfCharacterFromSet:[characterSet invertedSet]].location != NSNotFound) {
        return NO;
    }
    NSString *text = self.text;
    text = [text stringByReplacingCharactersInRange:range withString:string];
    text = [text stringByReplacingOccurrencesOfString:@" " withString:@""];
    
    NSMutableString *temString = [NSMutableString stringWithString:text];
    [temString insertString:@" " atIndex:0];
    text = temString;
    NSString *newString = @"";
    while (text.length > 0) {
        
        NSString *subString = [text substringToIndex:MIN(text.length, 4)];
        newString = [newString stringByAppendingString:subString];
        if (subString.length == 4) {
            newString = [newString stringByAppendingString:@" "];
        }
        text = [text substringFromIndex:MIN(text.length, 4)];
    }
    
    newString = [newString stringByTrimmingCharactersInSet:[characterSet invertedSet]];// 这一步把首尾两端不合规矩的字符去除掉
    
    if (newString.length > 13) {
        newString = [newString substringWithRange:NSMakeRange(0, 13)];
    }
    self.text = newString;
    successInputBlock();
    return NO;
}

2. 具体类中使用

// 添加kvo监听
[self.phoneField addObserver:self forKeyPath:@"text" options:NSKeyValueObservingOptionNew|NSKeyValueObservingOptionOld context:nil];

// 移除kvo监听，不移除在iOS9以下会闪退
- (void)dealloc{
    [self.phoneField removeObserver:self forKeyPath:@"text"];
}

// 监听到了textField改变时
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSKeyValueChangeKey,id> *)change context:(void *)context{
    if (object == self.phoneField  && [keyPath isEqualToString:@"text"]) {
        
        NSString *newNumber = change[NSKeyValueChangeNewKey];
        NSString *oldNumber = change[NSKeyValueChangeOldKey];
        if (![newNumber isEqualToString:oldNumber]) {
            [self textField:object shouldChangeCharactersInRange:NSMakeRange(0, [(UITextField *)object text].length) replacementString:newNumber];
        }
    }else{
        [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
    }
}

// 以下是代理方法
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
    
    if (textField == self.phoneField) {
        // 1. 键盘输入时 2.粘贴 3.KVO赋值 4.清除按钮点击
        
        return [textField phoneNumberFormatWithInputRange:range replacementString:string successInput:^{
            [self refreshSureBtnState];
        }];
    }else if(textField == self.bankCardNoField){
        
        return [textField bankCardFormatWithInputRange:range replacementString:string successInput:^{
            [self refreshSureBtnState];
        }];
    }
    return YES;
}

3. 以上完结