1. 自动添加其他字符串(空格)显示

-(BOOL)textField:(UITextField*)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
       NSString *text = [textField text];
       NSCharacterSet *characterSet = [NSCharacterSet characterSetWithCharactersInString:@"0123456789\b"];
       string = [string stringByReplacingOccurrencesOfString:@" " withString:@""];
       if ([string rangeOfCharacterFromSet:[characterSet invertedSet]].location != NSNotFound) {
               return NO;
           }
       text = [text stringByReplacingCharactersInRange:range withString:string];
       text = [text stringByReplacingOccurrencesOfString:@" " withString:@""];
    // 如果是电话号码格式化，需要添加这三行代码
        NSMutableString *temString = [NSMutableString stringWithString:text];
        [temString insertString:@" " atIndex:0];
        text = temString;
        NSString *newString = @"";
        while (text.length > 0) {
                NSString *subString = [text substringToIndex:MIN(text.length, 1)];
                newString = [newString stringByAppendingString:subString];
                if (subString.length == 1) {
                        newString = [newString stringByAppendingString:@" "];
                    }
                text = [text substringFromIndex:MIN(text.length, 1)];
            }
        newString = [newString stringByTrimmingCharactersInSet:[characterSet invertedSet]];
//        if (newString.length >= 14) {
//                return NO;
//            }
        [textField setText:newString];
        return NO;
}

2. 输入金额限制

限制条件:

1. 提现金额必须大于 20元
2. 只能输入两位小数
3. 不满足条件的 提交按钮不能点击

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
    //    限制只能输入数字
    BOOL isHaveDian = YES;
    if ([string isEqualToString:@" "]) {
        return NO;
    }
    if ([textField.text rangeOfString:@"."].location == NSNotFound) {
        isHaveDian = NO;
    }
    if ([string length] > 0) {
        //判断按钮是否可点击
        CGFloat  cashMoney = [self.cashMoney doubleValue];
        NSString *str =  [textField.text stringByReplacingCharactersInRange:range withString:string];
        if ([str doubleValue]>=[_showLimitMoney floatValue]&&[str doubleValue]<=cashMoney)
        {
            //按钮点击事件
            commitBtn.backgroundColor = greenColor;
            commitBtn.enabled = YES;
        }else
        {
            commitBtn.backgroundColor = cGrayLightColor;
            commitBtn.enabled = NO;
            return YES;
        }
        unichar single = [string characterAtIndex:0];//当前输入的字符
        if ((single >= '0' && single <= '9') || single == '.') {//数据格式正确
            if([textField.text length] == 0){
                if(single == '.') {
                    [textField.text stringByReplacingCharactersInRange:range withString:@""];
                    return NO;
                }
            }
            //输入的字符是否是小数点
            if (single == '.') {
                if(!isHaveDian)//text中还没有小数点
                {
                    isHaveDian = YES;
                    return YES;
                    
                }else{
                    [textField.text stringByReplacingCharactersInRange:range withString:@""];
                    return NO;
                }
            }else{
                if (isHaveDian) {//存在小数点
                    
                    //判断小数点的位数
                    NSRange ran = [textField.text rangeOfString:@"."];
                    if (range.location - ran.location <= 2) {
                        return YES;
                    }else{
                        return NO;
                    }
                }else{
                    return YES;
                }
            }
        }else{//输入的数据格式不正确
            
            [textField.text stringByReplacingCharactersInRange:range withString:@""];
            return NO;
        }
    }
    else
    {
        //判断按钮是否可点击
        CGFloat  cashMoney = [self.cashMoney doubleValue];
        NSString *str =  [textField.text stringByReplacingCharactersInRange:range withString:string];
        if ([str doubleValue]>=[_showLimitMoney doubleValue]&&[str doubleValue]<=cashMoney)
        {
            //按钮点击事件
            commitBtn.backgroundColor = greenColor;
            commitBtn.enabled = YES;
        }else
        {
            commitBtn.backgroundColor = cGrayLightColor;
            commitBtn.enabled = NO;
            return YES;
        }
        return YES;
    }
}