如何在iphone中将字节数组转换为base64字符串？

Question

我在vb中有一段代码。我需要将字节数组转换为 base 64 字符串。以下是vb代码。

如果 arrLicence.Count > 0 那么

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

我需要它在 iphone 中的等价物。我尝试使用 NSData 和 base64 转换，但结果延迟。

我已使用此链接进行转换。 http://www.cocoadev.com/index.pl?BaseSixtyFour

我尝试使用 memcpy 创建单个字节，然后创建一个数组，但没有成功。

我尝试过的如下：

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);

这导致 IJCgkA== 而 .NET 中的代码返回 ZDeB1A==

请注意，转换是针对 arrLicence 的前四个字节，输入是 64、37、81、d4

Answer 1

试试这个，希望对你有帮助。 get-base64-nsstring-from-nsdata

Answer 2

unsigned char *buffer = (unsigned char*)malloc(8);
buffer[0] =  [d1 bytes]  ;
buffer[1] =  [d2 bytes] ;
buffer[2] =  [d3 bytes] ;
buffer[3] =  [d4 bytes] ;

不确定您希望这样做。 bytes 返回一个数组，并且您将数组的地址分配给缓冲区的 char 元素。此缓冲区不会填充您期望的任何数据，来自 d2 的“数据”将部分覆盖来自 d1 等的数据。

此外，您不应该对字节数组的长度做出太多假设，尤其是在使用 UTF-16 时。

简而言之：您不会在转换例程中抛出您期望的数据。也许在调试器中检查一下。

Answer 3

查看代码示例，非常不言自明...

http://www.cocoadev.com/index.pl?BaseSixtyFour

还可以查看下面的 SO 帖子。

How do I do base64 encoding on iphone-sdk?

Answer 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;

此 commandToSend 然后被转换为 base64 数据。

Answer 5

如果您查看您给出的最后 2 个数字作为示例，您会注意到转换匹配。因为高低部分是一样的。

只需交换 hi 和 low 词。

Answer 6

您可以使用此 base64.h 和 base64.m 类解码为 base64 字符串。

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

如果有任何问题，请检查并告诉我。