//获取当前系统的时间戳
+(long)getTimeSp{
    long time;
    NSDate *fromdate=[NSDate date];
    time=(long)[fromdate timeIntervalSince1970];
    return time;
}

//将时间戳转换成NSDate
+(NSDate *)changeSpToTime:(NSString*)spString{
    NSDate *confromTimesp = [NSDate dateWithTimeIntervalSince1970:[spString intValue]];
    return confromTimesp;
}
//将时间戳转换成NSDate,加上时区偏移
+(NSDate*)zoneChange:(NSString*)spString{
    NSDate *confromTimesp = [NSDate dateWithTimeIntervalSince1970:[spString intValue]];
    NSTimeZone *zone = [NSTimeZone systemTimeZone];
    NSInteger interval = [zone secondsFromGMTForDate:confromTimesp];
    NSDate *localeDate = [confromTimesp  dateByAddingTimeInterval: interval];
    return localeDate;
}
//比较给定NSDate与当前时间的时间差，返回相差的秒数
+(long)timeDifference:(NSDate *)date{
    NSDate *localeDate = [NSDate date];
    long difference =fabs([localeDate timeIntervalSinceDate:date]);
    return difference;
}
//将NSDate按yyyy-MM-dd HH:mm:ss格式时间输出
+(NSString*)nsdateToString:(NSDate *)date{
    NSDateFormatter *dateFormat=[[NSDateFormatter alloc]init];
    [dateFormat setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
    NSString* string=[dateFormat stringFromDate:date];
    return string;
}
//将yyyy-MM-dd HH:mm:ss格式时间转换成时间戳
+(long)changeTimeToTimeSp:(NSString *)timeStr{
    long time;
    NSDateFormatter *format=[[NSDateFormatter alloc] init];
    [format setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
    NSDate *fromdate=[format dateFromString:timeStr];
    time= (long)[fromdate timeIntervalSince1970];
    [format release];
    return time;
}
//获取当前系统的yyyy-MM-dd HH:mm:ss格式时间
+(NSString *)getTime{
    NSDate *fromdate=[NSDate date];
    NSDateFormatter *dateFormat=[[NSDateFormatter alloc]init];
    [dateFormat setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
    NSString* string=[dateFormat stringFromDate:fromdate];
    return string;
}

点击下载DEMOhttp://www.kuaipan.cn/file/id_30491149655345667.htm 访问密码：At7uJx
//发送数据时,16进制数－>Byte数组->NSData,加上校验码部分
+(NSData *)hexToByteToNSData:(NSString *)str{
    int j=0;
    Byte bytes[[str length]/2];
    for(int i=0;i<[str length];i++)
    {
        int int_ch;  ///两位16进制数转化后的10进制数
        unichar hex_char1 = [str characterAtIndex:i]; ////两位16进制数中的第一位(高位*16)
        int int_ch1;
        if(hex_char1 >= ‘0‘ && hex_char1 <=‘9‘)
            int_ch1 = (hex_char1-48)*16;   //// 0 的Ascll - 48
        else if(hex_char1 >= ‘A‘ && hex_char1 <=‘F‘)
            int_ch1 = (hex_char1-55)*16; //// A 的Ascll - 65
        else
            int_ch1 = (hex_char1-87)*16; //// a 的Ascll - 97
        i++;
        unichar hex_char2 = [str characterAtIndex:i]; ///两位16进制数中的第二位(低位)
        int int_ch2;
        if(hex_char2 >= ‘0‘ && hex_char2 <=‘9‘)
            int_ch2 = (hex_char2-48); //// 0 的Ascll - 48
        else if(hex_char2 >= ‘A‘ && hex_char2 <=‘F‘)
            int_ch2 = hex_char2-55; //// A 的Ascll - 65
        else
            int_ch2 = hex_char2-87; //// a 的Ascll - 97
        int_ch = int_ch1+int_ch2;
        bytes[j] = int_ch;  ///将转化后的数放入Byte数组里
//        if (j==[str length]/2-2) {
//            int k=2;
//            int_ch=bytes[0]^bytes[1];
//            while (k
//                int_ch=int_ch^bytes[k];
//                k++;
//            }
//            bytes[j] = int_ch;
//        }
        j++;
    }
    NSData *newData = http://www.mamicode.com/[[NSData alloc] initWithBytes:bytes length:[str length]/2 ];
    NSLog(@"%@",newData);
    return newData;
}
//接收数据时,NSData－>Byte数组->16进制数
+(NSString *)NSDataToByteTohex:(NSData *)data{
    Byte *bytes = (Byte *)[data bytes];
    NSString *hexStr=@"";
    for(int i=0;i<[data length];i++)
    {
        NSString *newHexStr = [NSString stringWithFormat:@"%x",bytes[i]&0xff];///16进制数
        if([newHexStr length]==1)
            hexStr = [NSString stringWithFormat:@"%@0%@",hexStr,newHexStr];
        else
            hexStr = [NSString stringWithFormat:@"%@%@",hexStr,newHexStr];
    }
    NSLog(@"hexStr:%@",hexStr);
    return hexStr;
}
//将汉字字符串转换成16进制字符串
+(NSString *)chineseToHex:(NSString*)chineseStr{
    NSStringEncoding encodingGB18030= CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingGB_18030_2000);
    NSData *responseData =http://www.mamicode.com/[chineseStr dataUsingEncoding:encodingGB18030 ];
    NSString *string=[sendSocket NSDataToByteTohex:responseData];
    return string;
}
//将汉字字符串转换成UTF8字符串
+(NSString *)chineseToUTf8Str:(NSString*)chineseStr{
    NSStringEncoding encodingUTF8 = NSUTF8StringEncoding;
    NSData *responseData2 =[chineseStr dataUsingEncoding:encodingUTF8 ];
    NSString *string=[sendSocket NSDataToByteTohex:responseData2];
    return string;
}
//将十六进制字符串转换成汉字
+(NSString*)changeLanguage:(NSString*)chinese{
    NSString *strResult;
    NSLog(@"chinese:%@",chinese);
    if (chinese.length%2==0) {
        //第二次转换
        NSData *newData = [sendSocket hexToByteToNSData:chinese];
        unsigned long encode = CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingGB_18030_2000);
        strResult = [[NSString alloc] initWithData:newData encoding:encode];
        NSLog(@"strResult:%@",strResult);
    }else{
        NSString *strResult = @"已假定是汉字的转换，所传字符串的长度必须是4的倍数!";
        NSLog(@"%@",strResult);
        return NULL;
    }
    return strResult;
}
/////////////GBK,汉字，GB2312,ASCII码，UTF8,UTF16
//UTF8字符串转换成汉字
+(NSString*)changeLanguageUTF8:(NSString*)chinese{
    NSString *strResult;
    NSData *data=[sendSocket hexToByteToNSData:chinese];
    strResult=[[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding];
    return strResult;
}
//将十六进制数转换成十进制
-(NSString *)ToHex:(int)tmpid
{
    NSLog(@"tmpid:%d",tmpid);
    NSString *nLetterValue;
    NSString *str =@"";
    int ttmpig;
    for (int i = 0; i<9; i++) {
        ttmpig=tmpid;
        tmpid=tmpid/16;
        switch (ttmpig)
        {
            case 10:
                nLetterValue =http://www.mamicode.com/@"A";break;
            case 11:
                nLetterValue =http://www.mamicode.com/@"B";break;
            case 12:
                nLetterValue =http://www.mamicode.com/@"C";break;
            case 13:
                nLetterValue =http://www.mamicode.com/@"D";break;
            case 14:
                nLetterValue =http://www.mamicode.com/@"E";break;
            case 15:
                nLetterValue =http://www.mamicode.com/@"F";break;
            default:nLetterValue=http://www.mamicode.com/[[NSString alloc]initWithFormat:@"%i",ttmpig];               
        }       
        str = [nLetterValue stringByAppendingString:str];
        NSLog(@"str:%@",str);
        if (tmpid == 0) {
            break;
        }       
    }
    return str;
}
//Unicode转化为汉字
+ (NSString *)replaceUnicode1:(NSString *)unicodeStr {
    NSString *tempStr1 = [unicodeStr stringByReplacingOccurrencesOfString:@"\\u"withString:@"\\U"];
    NSString *tempStr2 = [tempStr1 stringByReplacingOccurrencesOfString:@"""withString:@"\\""];
    NSString *tempStr3 = [[@"""stringByAppendingString:tempStr2]stringByAppendingString:@"""];
    NSData *tempData = http://www.mamicode.com/[tempStr3 dataUsingEncoding:NSUTF8StringEncoding];
    NSString* returnStr = [NSPropertyListSerialization propertyListFromData:tempData mutabilityOption:NSPropertyListImmutable format:NULL errorDescription:NULL];
    return [returnStr stringByReplacingOccurrencesOfString:@"\\r\\n"withString:@"\n"];
}

//iso8859－1 到 unicode编码转换

+ (NSString *)changeISO88591StringToUnicodeString:(NSString *)iso88591String

{

    NSMutableString *srcString = [[[NSMutableString alloc]initWithString:iso88591String] autorelease];

    [srcString replaceOccurrencesOfString:@"&" withString:@"&" options:NSLiteralSearch range:NSMakeRange(0, [srcString length])];

    [srcString replaceOccurrencesOfString:@"&加行末位两个字符" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [srcString length])];//#x

    NSMutableString *desString = [[[NSMutableString alloc]init] autorelease];

    NSArray *arr = [srcString componentsSeparatedByString:@";"];

    for(int i=0;i<[arr count]-1;i++){

        NSString *v = [arr objectAtIndex:i];

        char *c = malloc(3);

        int value = http://www.mamicode.com/[StringUtil changeHexStringToDecimal:v];//将二进制转化为十进制

        c[1] = value  &0x00FF;

        c[0] = value >>8 &0x00FF;

        c[2] = ‘‘;

        [desString appendString:[NSString stringWithCString:c encoding:NSUnicodeStringEncoding]];

        free(c);

    }

    return desString;

}

 

 

NSString转换成URL编码

stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding

还原：

stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding

 

 

//十六进制数转十进制数，因为苹果采用的是小端模式，取第一个字符是取最高位数，取最后一个字符是个位数。所以需要乘以16的tmpid.length-i-1次方

-(int)TotexHex1:(NSString*)tmpid

{    

    int int_ch1=0;

    for(int i=0;i

        unichar hex_char = [tmpid characterAtIndex:i];

        int int_ch;

        if(hex_char >= ‘0‘ && hex_char <=‘9‘)

            int_ch = (hex_char-48); //// 0 的Ascll - 48

        else if(hex_char >= ‘A‘ && hex_char <=‘F‘)

            int_ch = (hex_char-55); //// A 的Ascll - 65

        else

            int_ch = (hex_char-87); //// a 的Ascll - 97

        int_ch=int_ch*pow( 16, tmpid.length-i-1 );//pow的第二个参数根据小端模式或者大端模式调整，

        int_ch1 = int_ch1+int_ch;

        NSLog(@"%d",int_ch1);

    }

    return int_ch1;

}