swift：

// MARK: -  判断字符串是否符合标准
extension String {
    
    ///  根据设置个数判断 数字是否有通过
    /// - Parameter textF: 输入框
    /// - Parameter range: 输入位置
    /// - Parameter importStr: 输入字符
    /// - Parameter prePointCount: 小数点前个数(默认9)
    /// - Parameter behindPointCount: 小数点后个数(默认2)
    func checkTextF(textF: UITextField, changeCharactersInRange range: NSRange, importStr: String, prePointCount: Int = 9, behindPointCount: Int = 2) -> Bool {
        if importStr.isEmpty == true {
            return true
        }
        if textF.text?.contains(".") == true { // 只能输入一个.
            if importStr == "." {
                return false
            }
            if textF.text?.length ?? 0 >= prePointCount + behindPointCount + 1 {
                log("没有小数点 不能输入超过限额")
                return false
            }
            // 判断小数点位数
            guard let ran = textF.text?.range(of: ".") else { return false}
            guard let ran1 = textF.text?.toNSRange(ran) else { return false}
            if range.location > ran1.location {//小数点后边输入
                if (textF.text?.length ?? 0) - ran1.location == behindPointCount + 1 {
                    return false
                }
                return true
            }else {//小数点前边输入
                if (textF.text?.length ?? 0) >= prePointCount + behindPointCount + 1 {
                    log("没有小数点 不能输入超过限额 ");
                    return false
                }
                return true
            }
     
        }else {//无小数
            if textF.text?.length ?? 0 >= prePointCount {
                if importStr == "." {
                    return true
                }
                if importStr == "" {
                    return true
                }
                return false
            }
        }

        if textF.text == "0" {//0后面只能输入.
           return importStr == "." ?  true : false
        }
        if importStr == " " {
            return false
        }
        
        return true
    }

}

OC:

/**
 根据设置个数判断 数字是否有通过

 @param textField 输入框
 @param range 输入位置
 @param string 输入字符
 @param prePointCount 小数点前个数
 @param behindPointCount 小数点后个数
 @return 是否通过
 */
+(BOOL )checkTextF:(UITextField *)textField ChangeCharactersInRange:(NSRange)range importStr:(NSString *)string prePointCount:(NSInteger )prePointCount behindPointCount:(NSInteger )behindPointCount{
    if ([string isEqualToString:@""]) {
        return YES;
    }
    if ([textField.text containsString:@"."]) {//只能输入一个.
        if ([string isEqualToString:@"."]) {
            return NO;
        }
        
        if (textField.text.length >= prePointCount +  behindPointCount + 1) {
            NSLog(@"没有小数点 不能输入超过 123456.123456 ");
            return NO;
        }
        //判断小数点的位数
        NSRange ran = [textField.text rangeOfString:@"."];
        NSLog(@"ran.location : %ld,range.location : %ld",ran.location,range.location);
        if (range.location > ran.location) {//小数点后边输入
            if (textField.text.length - ran.location == behindPointCount + 1) {
                return NO;
            }
            return YES;
        }else{//小数点前边输入
            if (textField.text.length >= prePointCount + behindPointCount +1) {
                NSLog(@"没有小数点 不能输入超过 10 0000 ");
                return NO;
            }
            return YES;
            
        }
    }else{//无小数
        if (textField.text.length >= prePointCount) {
            if ([string isEqualToString:@"."]) {
                return YES;
            }
            if ([string isEqualToString:@""]) {
                return YES;
            }
            
            return NO;
        }
        
        
    }
    
    if ([textField.text isEqualToString:@"0"]) {//0后面只能输入.
        if ([string isEqualToString:@"."]) {
            return YES;
        }else{
            return NO;
        }
    }
    
    if ([string isEqualToString:@" "]) {
        return NO;
    }
    
    return YES;
    
}