比特串处理

#import <Foundation/Foundation.h>

@interface ByteUnit : NSObject

//返回指定字节的10进制数

+(unsigned long)subDataLength:(NSData*)_didReadData startCount:(int)_startCount lenghtCount:(int)_lengthCount;

//将字节转为字符串形式

+(NSString *)byteToString:(NSData *)data startCount:(int)_startCount lenghtCount:(int)_lengthCount;

//字符串转字节数据

+(NSData*)stringToByte:(NSString*)string;

@end

// ByteUnit.m

// SmartHomeWIFI

// Created by 深圳市秀软科技有限公司 on 14-2-18.

#import "ByteUnit.h"

@implementation ByteUnit

//获取数据长度。固定标准 4控制+4长度

+(unsigned long)subDataLength:(NSData*)_didReadData startCount:(int)_startCount lenghtCount:(int)_lengthCount

{

unsigned long loc_length = 0;

if (_didReadData.length >= _startCount+_lengthCount) {

Byte *testByte = (Byte *)[_didReadData bytes];

NSString *loc_string = @"";

for (int i = 0 ; i <_lengthCount; i++) {

unsigned long loc_length1 = testByte[_startCount+i];

loc_string =[NSString stringWithFormat:@"%@%.2lx",loc_string,loc_length1];

//[[NSString stringWithFormat:@"%.2lx",loc_length1] stringByAppendingString:loc_string];//反

// NSLog(@"hejiang:%@",loc_string);

}

// unsigned long loc_length1 = testByte[4];

// unsigned long loc_length2 = testByte[5];

// unsigned long loc_length3 = testByte[6];

// unsigned long loc_length4 = testByte[7];

// NSString *loc_string = [NSString stringWithFormat:@"%.2lx%.2lx%.2lx%.2lx",loc_length4,loc_length3,loc_length2,loc_length1];

unsigned long red = strtoul([loc_string UTF8String],0,16);

loc_length = red;

}

return loc_length;

// if(_lengthCount==2)

// return htons(loc_length);

// else

// return htonl(loc_length);

}

+(NSString *)byteToString:(NSData *)data startCount:(int)_startCount lenghtCount:(int)_lengthCount

{

NSData *dataT=[data subdataWithRange:NSMakeRange(_startCount, _lengthCount)];

NSString *str=[[NSString alloc]initWithData:dataT encoding:NSUTF8StringEncoding];

return str;

NSString *loc_string = @"";

if (data.length >= _startCount+_lengthCount) {

Byte *testByte = (Byte *)[data bytes];

for (int i = 0 ; i <_lengthCount; i++) {

unsigned long loc_length1 = testByte[_startCount+i];

loc_string = [NSString stringWithFormat:@"%@%.lx",loc_string,loc_length1];

}

return loc_string;

}

+(NSData*)stringToByte:(NSString*)string

{

NSString *hexString=[[string uppercaseString] stringByReplacingOccurrencesOfString:@" "withString:@""];

if ([hexString length]%2!=0) {

return nil;

}

Byte tempbyt[1]={0};

NSMutableData* bytes=[NSMutableDatadata];

for(int i=0;i<[hexString length];i++)

{

unichar hex_char1 = [hexString 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

return nil;

i++;

unichar hex_char2 = [hexString 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

return nil;

tempbyt[0] = int_ch1+int_ch2; ///将转化后的数放入Byte数组里

[bytes appendBytes:tempbyt length:1];

}

return bytes;

}

@end