问题
I have a piece of code in vb. I need to convert array of bytes to base 64 string. Following is the vb code.
If arrLicence.Count > 0 Then
LicenceBytes = CType(Array.CreateInstance(GetType(Byte),6), Byte())
LicenceBytes(0) = Convert.ToByte(arrLicence(0).ToString(), 16) LicenceBytes(1) = Convert.ToByte(arrLicence(1).ToString(), 16) LicenceBytes(2) = Convert.ToByte(arrLicence(2).ToString(), 16) LicenceBytes(3) = Convert.ToByte(arrLicence(3).ToString(), 16) LicenceBytes(4) = Convert.ToByte(arrLicence(4).ToString(), 16) LicenceBytes(5) = Convert.ToByte(arrLicence(5).ToString(), 16) LicenceString = Convert.ToBase64String(LicenceBytes) '6 byteArray - passed by the user - Base64Encoded
I need its equivalent in iphone. I tried with NSData and base64 conversion but result defers.
I have used this link for conversion. http://www.cocoadev.com/index.pl?BaseSixtyFour
I tried by creating individual bytes using memcpy and then creating an array but with no success.
What I have tried is as follows:
NSData *d1 =[@"64" dataUsingEncoding:NSUTF16StringEncoding];
NSData *d2 = [@"37" dataUsingEncoding:NSUTF16StringEncoding];
NSData *d3 = [@"81" dataUsingEncoding:NSUTF16StringEncoding];
NSData *d4 = [@"d4" dataUsingEncoding:NSUTF16StringEncoding];
unsigned char *buffer = (unsigned char*)malloc(8);
buffer[0] = [d1 bytes] ;
buffer[1] = [d2 bytes] ;
buffer[2] = [d3 bytes] ;
buffer[3] = [d4 bytes] ;
NSData *data = [NSData dataWithBytes:buffer length:4];
NSString *str = [self encodeBase64WithData:data];
free(buffer);
This results in IJCgkA== while code in .NET returns ZDeB1A==
Please note that the conversion is for first four bytes of arrLicence and the input is 64, 37, 81, d4
回答1:
Try this one, i hope this will surely help you. get-base64-nsstring-from-nsdata
回答2:
unsigned char *buffer = (unsigned char*)malloc(8);
buffer[0] = [d1 bytes] ;
buffer[1] = [d2 bytes] ;
buffer[2] = [d3 bytes] ;
buffer[3] = [d4 bytes] ;
Not sure what you expect this to do. bytes return an array, and you are assigning the addresses of the arrays to char elements of your buffer. This buffer won't be filled with any of the data you expect, and the "data" from d2 will partially overwrite those from d1 etc.
Also, you shouldn't make much assumptions about the lengths of your byte arrays, especially not if using UTF-16.
In a word: You don't throw the data you expect at your conversion routine. Maybe check that in the debugger.
回答3:
See code sample, Very self-explained ...
http://www.cocoadev.com/index.pl?BaseSixtyFour
Also check below SO post .
How do I do base64 encoding on iphone-sdk?
回答4:
//strBusiCode = @"64-37-81-d4-39-6d";
NSArray *tmp_arr = [strBusiCode componentsSeparatedByString:@"-"];
NSMutableData *commandToSend= [[NSMutableData alloc] init];
unsigned char whole_byte;
char byte_chars[3] = {'\0','\0','\0'};
int i;
for (i=0; i < [tmp_arr count]; i++) {
byte_chars[0] = [[tmp_arr objectAtIndex:i] characterAtIndex:0];
byte_chars[1] = [[tmp_arr objectAtIndex:i] characterAtIndex:1];
whole_byte = strtol(byte_chars, NULL, 16);
[commandToSend appendBytes:&whole_byte length:1];
}
return commandToSend;
This commandToSend is then converted to base64 data.
回答5:
If you look at the 2 last numbers you give as example, you will notice conversion match. Because the hi and low parts are the same.
Just swap the hi and low words.
回答6:
You can use this base64.h and base64.m class to decode to base64 string.
base64.h
#import <Foundation/Foundation.h>
@interface NSData (Base64)
+ (NSData *)dataWithBase64EncodedString:(NSString *)string;
- (id)initWithBase64EncodedString:(NSString *)string;
- (NSString *) base64Encoding;
- (NSString *) base64EncodingWithLineLength:(unsigned int) lineLength;
@end
base64.m
#import "base64.h"
static char encodingTable[64] = {
'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P',
'Q','R','S','T','U','V','W','X','Y','Z','a','b','c','d','e','f',
'g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v',
'w','x','y','z','0','1','2','3','4','5','6','7','8','9','+','/' };
@implementation NSData (VQBase64)
- (id)initWithString:(NSString *)string {
if (self = [super init]) {
[self initWithBase64EncodedString:string];
}
return self;
}
+ (NSData *) dataWithBase64EncodedString:(NSString *) string {
return [[[NSData allocWithZone:nil] initWithBase64EncodedString:string] autorelease];
}
- (id) initWithBase64EncodedString:(NSString *) string {
NSMutableData *mutableData = nil;
if( string ) {
unsigned long ixtext = 0;
unsigned long lentext = 0;
unsigned char ch = 0;
unsigned char inbuf[4], outbuf[3];
short i = 0, ixinbuf = 0;
BOOL flignore = NO;
BOOL flendtext = NO;
NSData *base64Data = nil;
const unsigned char *base64Bytes = nil;
// Convert the string to ASCII data.
base64Data = [string dataUsingEncoding:NSASCIIStringEncoding];
base64Bytes = [base64Data bytes];
mutableData = [NSMutableData dataWithCapacity:[base64Data length]];
lentext = [base64Data length];
while( YES ) {
if( ixtext >= lentext ) break;
ch = base64Bytes[ixtext++];
flignore = NO;
if( ( ch >= 'A' ) && ( ch <= 'Z' ) ) ch = ch - 'A';
else if( ( ch >= 'a' ) && ( ch <= 'z' ) ) ch = ch - 'a' + 26;
else if( ( ch >= '0' ) && ( ch <= '9' ) ) ch = ch - '0' + 52;
else if( ch == '+' ) ch = 62;
else if( ch == '=' ) flendtext = YES;
else if( ch == '/' ) ch = 63;
else flignore = YES;
if( ! flignore ) {
short ctcharsinbuf = 3;
BOOL flbreak = NO;
if( flendtext ) {
if( ! ixinbuf ) break;
if( ( ixinbuf == 1 ) || ( ixinbuf == 2 ) ) ctcharsinbuf = 1;
else ctcharsinbuf = 2;
ixinbuf = 3;
flbreak = YES;
}
inbuf [ixinbuf++] = ch;
if( ixinbuf == 4 ) {
ixinbuf = 0;
outbuf [0] = ( inbuf[0] << 2 ) | ( ( inbuf[1] & 0x30) >> 4 );
outbuf [1] = ( ( inbuf[1] & 0x0F ) << 4 ) | ( ( inbuf[2] & 0x3C ) >> 2 );
outbuf [2] = ( ( inbuf[2] & 0x03 ) << 6 ) | ( inbuf[3] & 0x3F );
for( i = 0; i < ctcharsinbuf; i++ )
[mutableData appendBytes:&outbuf[i] length:1];
}
if( flbreak ) break;
}
}
}
self = [self initWithData:mutableData];
return self;
}
- (NSString *) base64Encoding {
return [self base64EncodingWithLineLength:0];
}
- (NSString *) base64EncodingWithLineLength:(unsigned int) lineLength {
const unsigned char *bytes = [self bytes];
NSMutableString *result = [NSMutableString stringWithCapacity:[self length]];
unsigned long ixtext = 0;
unsigned long lentext = [self length];
long ctremaining = 0;
unsigned char inbuf[3], outbuf[4];
unsigned short i = 0;
unsigned short charsonline = 0, ctcopy = 0;
unsigned long ix = 0;
while( YES ) {
ctremaining = lentext - ixtext;
if( ctremaining <= 0 ) break;
for( i = 0; i < 3; i++ ) {
ix = ixtext + i;
if( ix < lentext ) inbuf[i] = bytes[ix];
else inbuf [i] = 0;
}
outbuf [0] = (inbuf [0] & 0xFC) >> 2;
outbuf [1] = ((inbuf [0] & 0x03) << 4) | ((inbuf [1] & 0xF0) >> 4);
outbuf [2] = ((inbuf [1] & 0x0F) << 2) | ((inbuf [2] & 0xC0) >> 6);
outbuf [3] = inbuf [2] & 0x3F;
ctcopy = 4;
switch( ctremaining ) {
case 1:
ctcopy = 2;
break;
case 2:
ctcopy = 3;
break;
}
for( i = 0; i < ctcopy; i++ )
[result appendFormat:@"%c", encodingTable[outbuf[i]]];
for( i = ctcopy; i < 4; i++ )
[result appendString:@"="];
ixtext += 3;
charsonline += 4;
if( lineLength > 0 ) {
if( charsonline >= lineLength ) {
charsonline = 0;
[result appendString:@"\n"];
}
}
}
return [NSString stringWithString:result];
}
@end
Please check and let me know if any issue.
来源：https://stackoverflow.com/questions/6466083/how-to-convert-array-of-bytes-to-base64-string-in-iphone