iPhoneの圧縮API
IPhoneで使用できる圧縮APIはありますか？ iPhoneアプリが通信するためのRESTful Webサービスをいくつか構築していますが、効率化のために少なくとも一部の会話を圧縮する必要があります。
私は、形式（Zip、LHAなど）が何であるかを気にしません。安全である必要はありません。
一部の回答者は、サーバーは出力を圧縮でき、iPhoneはそれを消費できると指摘しています。私たちが持っているシナリオは、まさにその逆です。圧縮されたコンテンツをPOSTしますto Webサービス。圧縮の逆は関係ありません。
zlibとbzip2が利用可能です。そして、それらが（一般的に）OS Xでコンパイルされる限り、いつでも他のものを追加できます。
最小ファイルサイズにはbzip2が適していますが、圧縮と解凍にはより多くのCPUパワーが必要です。
また、Webサービスと通信しているため、それほど多くのことを行う必要がない場合もあります。 NSURLRequest gzipエンコーディングを受け入れるサーバーの応答で透過的に。
会話のデータをNSDataオブジェクトに保存すると、CocoaDev wikiの人々が NSData category を投稿して、gzipとzlibの圧縮/解凍を簡単な方法として追加します。これらは 私のiPhoneアプリケーション でうまく機能しました。
CocoaDev wikiが新しいホストに移動されている間に上記のリンクが機能しなくなったため、このカテゴリ全体を以下に再現しました。
インターフェース：
@interface NSData (NSDataExtension)
// Returns range [start, null byte), or (NSNotFound, 0).
- (NSRange) rangeOfNullTerminatedBytesFrom:(int)start;
// Canonical Base32 encoding/decoding.
+ (NSData *) dataWithBase32String:(NSString *)base32;
- (NSString *) base32String;
// COBS is an encoding that eliminates 0x00.
- (NSData *) encodeCOBS;
- (NSData *) decodeCOBS;
// ZLIB
- (NSData *) zlibInflate;
- (NSData *) zlibDeflate;
// GZIP
- (NSData *) gzipInflate;
- (NSData *) gzipDeflate;
//CRC32
- (unsigned int)crc32;
// Hash
- (NSData*) md5Digest;
- (NSString*) md5DigestString;
- (NSData*) sha1Digest;
- (NSString*) sha1DigestString;
- (NSData*) ripemd160Digest;
- (NSString*) ripemd160DigestString;
@end
実装：
#import "NSData+CocoaDevUsersAdditions.h"
#include <zlib.h>
#include <openssl/md5.h>
#include <openssl/sha.h>
#include <openssl/ripemd.h>
@implementation NSData (NSDataExtension)
// Returns range [start, null byte), or (NSNotFound, 0).
- (NSRange) rangeOfNullTerminatedBytesFrom:(int)start
{
const Byte *pdata = [self bytes];
int len = [self length];
if (start < len)
{
const Byte *end = memchr (pdata + start, 0x00, len - start);
if (end != NULL) return NSMakeRange (start, end - (pdata + start));
}
return NSMakeRange (NSNotFound, 0);
}
+ (NSData *) dataWithBase32String:(NSString *)encoded
{
/* First valid character that can be indexed in decode lookup table */
static int charDigitsBase = '2';
/* Lookup table used to decode() characters in encoded strings */
static int charDigits[] =
{ 26,27,28,29,30,31,-1,-1,-1,-1,-1,-1,-1,-1 // 23456789:;<=>?
,-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10,11,12,13,14 // @ABCDEFGHIJKLMNO
,15,16,17,18,19,20,21,22,23,24,25,-1,-1,-1,-1,-1 // PQRSTUVWXYZ[\]^_
,-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10,11,12,13,14 // `abcdefghijklmno
,15,16,17,18,19,20,21,22,23,24,25 // pqrstuvwxyz
};
if (! [encoded canBeConvertedToEncoding:NSASCIIStringEncoding]) return nil;
const char *chars = [encoded cStringUsingEncoding:NSASCIIStringEncoding]; // avoids using characterAtIndex.
int charsLen = [encoded lengthOfBytesUsingEncoding:NSASCIIStringEncoding];
// Note that the code below could detect non canonical Base32 length within the loop. However canonical Base32 length can be tested before entering the loop.
// A canonical Base32 length modulo 8 cannot be:
// 1 (aborts discarding 5 bits at STEP n=0 which produces no byte),
// 3 (aborts discarding 7 bits at STEP n=2 which produces no byte),
// 6 (aborts discarding 6 bits at STEP n=1 which produces no byte).
switch (charsLen & 7) { // test the length of last subblock
case 1: // 5 bits in subblock: 0 useful bits but 5 discarded
case 3: // 15 bits in subblock: 8 useful bits but 7 discarded
case 6: // 30 bits in subblock: 24 useful bits but 6 discarded
return nil; // non-canonical length
}
int charDigitsLen = sizeof(charDigits);
int bytesLen = (charsLen * 5) >> 3;
Byte bytes[bytesLen];
int bytesOffset = 0, charsOffset = 0;
// Also the code below does test that other discarded bits
// (1 to 4 bits at end) are effectively 0.
while (charsLen > 0)
{
int digit, lastDigit;
// STEP n = 0: Read the 1st Char in a 8-Chars subblock
// Leave 5 bits, asserting there's another encoding Char
if ((digit = (int)chars[charsOffset] - charDigitsBase) < 0 || digit >= charDigitsLen || (digit = charDigits[digit]) == -1)
return nil; // invalid character
lastDigit = digit << 3;
// STEP n = 5: Read the 2nd Char in a 8-Chars subblock
// Insert 3 bits, leave 2 bits, possibly trailing if no more Char
if ((digit = (int)chars[charsOffset + 1] - charDigitsBase) < 0 || digit >= charDigitsLen || (digit = charDigits[digit]) == -1)
return nil; // invalid character
bytes[bytesOffset] = (Byte)((digit >> 2) | lastDigit);
lastDigit = (digit & 3) << 6;
if (charsLen == 2) {
if (lastDigit != 0) return nil; // non-canonical end
break; // discard the 2 trailing null bits
}
// STEP n = 2: Read the 3rd Char in a 8-Chars subblock
// Leave 7 bits, asserting there's another encoding Char
if ((digit = (int)chars[charsOffset + 2] - charDigitsBase) < 0 || digit >= charDigitsLen || (digit = charDigits[digit]) == -1)
return nil; // invalid character
lastDigit |= (Byte)(digit << 1);
// STEP n = 7: Read the 4th Char in a 8-chars Subblock
// Insert 1 bit, leave 4 bits, possibly trailing if no more Char
if ((digit = (int)chars[charsOffset + 3] - charDigitsBase) < 0 || digit >= charDigitsLen || (digit = charDigits[digit]) == -1)
return nil; // invalid character
bytes[bytesOffset + 1] = (Byte)((digit >> 4) | lastDigit);
lastDigit = (Byte)((digit & 15) << 4);
if (charsLen == 4) {
if (lastDigit != 0) return nil; // non-canonical end
break; // discard the 4 trailing null bits
}
// STEP n = 4: Read the 5th Char in a 8-Chars subblock
// Insert 4 bits, leave 1 bit, possibly trailing if no more Char
if ((digit = (int)chars[charsOffset + 4] - charDigitsBase) < 0 || digit >= charDigitsLen || (digit = charDigits[digit]) == -1)
return nil; // invalid character
bytes[bytesOffset + 2] = (Byte)((digit >> 1) | lastDigit);
lastDigit = (Byte)((digit & 1) << 7);
if (charsLen == 5) {
if (lastDigit != 0) return nil; // non-canonical end
break; // discard the 1 trailing null bit
}
// STEP n = 1: Read the 6th Char in a 8-Chars subblock
// Leave 6 bits, asserting there's another encoding Char
if ((digit = (int)chars[charsOffset + 5] - charDigitsBase) < 0 || digit >= charDigitsLen || (digit = charDigits[digit]) == -1)
return nil; // invalid character
lastDigit |= (Byte)(digit << 2);
// STEP n = 6: Read the 7th Char in a 8-Chars subblock
// Insert 2 bits, leave 3 bits, possibly trailing if no more Char
if ((digit = (int)chars[charsOffset + 6] - charDigitsBase) < 0 || digit >= charDigitsLen || (digit = charDigits[digit]) == -1)
return nil; // invalid character
bytes[bytesOffset + 3] = (Byte)((digit >> 3) | lastDigit);
lastDigit = (Byte)((digit & 7) << 5);
if (charsLen == 7) {
if (lastDigit != 0) return nil; // non-canonical end
break; // discard the 3 trailing null bits
}
// STEP n = 3: Read the 8th Char in a 8-Chars subblock
// Insert 5 bits, leave 0 bit, next encoding Char may not exist
if ((digit = (int)chars[charsOffset + 7] - charDigitsBase) < 0 || digit >= charDigitsLen || (digit = charDigits[digit]) == -1)
return nil; // invalid character
bytes[bytesOffset + 4] = (Byte)(digit | lastDigit);
//// This point is always reached for chars.length multiple of 8
charsOffset += 8;
bytesOffset += 5;
charsLen -= 8;
}
// On loop exit, discard the n trailing null bits
return [NSData dataWithBytes:bytes length:sizeof(bytes)];
}
- (NSString *) base32String
{
/* Lookup table used to canonically encode() groups of data bits */
static char canonicalChars[] =
{ 'A','B','C','D','E','F','G','H','I','J','K','L','M' // 00..12
,'N','O','P','Q','R','S','T','U','V','W','X','Y','Z' // 13..25
,'2','3','4','5','6','7' // 26..31
};
const Byte *bytes = [self bytes];
int bytesOffset = 0, bytesLen = [self length];
int charsOffset = 0, charsLen = ((bytesLen << 3) + 4) / 5;
char chars[charsLen];
while (bytesLen != 0) {
int digit, lastDigit;
// INVARIANTS FOR EACH STEP n in [0..5[; digit in [0..31[;
// The remaining n bits are already aligned on top positions
// of the 5 least bits of digit, the other bits are 0.
////// STEP n = 0: insert new 5 bits, leave 3 bits
digit = bytes[bytesOffset] & 255;
chars[charsOffset] = canonicalChars[digit >> 3];
lastDigit = (digit & 7) << 2;
if (bytesLen == 1) { // put the last 3 bits
chars[charsOffset + 1] = canonicalChars[lastDigit];
break;
}
////// STEP n = 3: insert 2 new bits, then 5 bits, leave 1 bit
digit = bytes[bytesOffset + 1] & 255;
chars[charsOffset + 1] = canonicalChars[(digit >> 6) | lastDigit];
chars[charsOffset + 2] = canonicalChars[(digit >> 1) & 31];
lastDigit = (digit & 1) << 4;
if (bytesLen == 2) { // put the last 1 bit
chars[charsOffset + 3] = canonicalChars[lastDigit];
break;
}
////// STEP n = 1: insert 4 new bits, leave 4 bit
digit = bytes[bytesOffset + 2] & 255;
chars[charsOffset + 3] = canonicalChars[(digit >> 4) | lastDigit];
lastDigit = (digit & 15) << 1;
if (bytesLen == 3) { // put the last 1 bits
chars[charsOffset + 4] = canonicalChars[lastDigit];
break;
}
////// STEP n = 4: insert 1 new bit, then 5 bits, leave 2 bits
digit = bytes[bytesOffset + 3] & 255;
chars[charsOffset + 4] = canonicalChars[(digit >> 7) | lastDigit];
chars[charsOffset + 5] = canonicalChars[(digit >> 2) & 31];
lastDigit = (digit & 3) << 3;
if (bytesLen == 4) { // put the last 2 bits
chars[charsOffset + 6] = canonicalChars[lastDigit];
break;
}
////// STEP n = 2: insert 3 new bits, then 5 bits, leave 0 bit
digit = bytes[bytesOffset + 4] & 255;
chars[charsOffset + 6] = canonicalChars[(digit >> 5) | lastDigit];
chars[charsOffset + 7] = canonicalChars[digit & 31];
//// This point is always reached for bytes.length multiple of 5
bytesOffset += 5;
charsOffset += 8;
bytesLen -= 5;
}
return [NSString stringWithCString:chars length:sizeof(chars)];
}
#define FinishBlock(X) \
(*code_ptr = (X), \
code_ptr = dst++, \
code = 0x01)
- (NSData *) encodeCOBS
{
if ([self length] == 0) return self;
NSMutableData *encoded = [NSMutableData dataWithLength:([self length] + [self length] / 254 + 1)];
unsigned char *dst = [encoded mutableBytes];
const unsigned char *ptr = [self bytes];
unsigned long length = [self length];
const unsigned char *end = ptr + length;
unsigned char *code_ptr = dst++;
unsigned char code = 0x01;
while (ptr < end)
{
if (*ptr == 0) FinishBlock(code);
else
{
*dst++ = *ptr;
code++;
if (code == 0xFF) FinishBlock(code);
}
ptr++;
}
FinishBlock(code);
[encoded setLength:((Byte *)dst - (Byte *)[encoded mutableBytes])];
return [NSData dataWithData:encoded];
}
- (NSData *) decodeCOBS
{
if ([self length] == 0) return self;
const Byte *ptr = [self bytes];
unsigned length = [self length];
NSMutableData *decoded = [NSMutableData dataWithLength:length];
Byte *dst = [decoded mutableBytes];
Byte *basedst = dst;
const unsigned char *end = ptr + length;
while (ptr < end)
{
int i, code = *ptr++;
for (i=1; i<code; i++) *dst++ = *ptr++;
if (code < 0xFF) *dst++ = 0;
}
[decoded setLength:(dst - basedst)];
return [NSData dataWithData:decoded];
}
- (NSData *)zlibInflate
{
if ([self length] == 0) return self;
unsigned full_length = [self length];
unsigned half_length = [self length] / 2;
NSMutableData *decompressed = [NSMutableData dataWithLength: full_length + half_length];
BOOL done = NO;
int status;
z_stream strm;
strm.next_in = (Bytef *)[self bytes];
strm.avail_in = [self length];
strm.total_out = 0;
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
if (inflateInit (&strm) != Z_OK) return nil;
while (!done)
{
// Make sure we have enough room and reset the lengths.
if (strm.total_out >= [decompressed length])
[decompressed increaseLengthBy: half_length];
strm.next_out = [decompressed mutableBytes] + strm.total_out;
strm.avail_out = [decompressed length] - strm.total_out;
// Inflate another chunk.
status = inflate (&strm, Z_SYNC_FLUSH);
if (status == Z_STREAM_END) done = YES;
else if (status != Z_OK) break;
}
if (inflateEnd (&strm) != Z_OK) return nil;
// Set real length.
if (done)
{
[decompressed setLength: strm.total_out];
return [NSData dataWithData: decompressed];
}
else return nil;
}
- (NSData *)zlibDeflate
{
if ([self length] == 0) return self;
z_stream strm;
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
strm.total_out = 0;
strm.next_in=(Bytef *)[self bytes];
strm.avail_in = [self length];
// Compresssion Levels:
// Z_NO_COMPRESSION
// Z_BEST_SPEED
// Z_BEST_COMPRESSION
// Z_DEFAULT_COMPRESSION
if (deflateInit(&strm, Z_DEFAULT_COMPRESSION) != Z_OK) return nil;
NSMutableData *compressed = [NSMutableData dataWithLength:16384]; // 16K chuncks for expansion
do {
if (strm.total_out >= [compressed length])
[compressed increaseLengthBy: 16384];
strm.next_out = [compressed mutableBytes] + strm.total_out;
strm.avail_out = [compressed length] - strm.total_out;
deflate(&strm, Z_FINISH);
} while (strm.avail_out == 0);
deflateEnd(&strm);
[compressed setLength: strm.total_out];
return [NSData dataWithData: compressed];
}
- (NSData *)gzipInflate
{
if ([self length] == 0) return self;
unsigned full_length = [self length];
unsigned half_length = [self length] / 2;
NSMutableData *decompressed = [NSMutableData dataWithLength: full_length + half_length];
BOOL done = NO;
int status;
z_stream strm;
strm.next_in = (Bytef *)[self bytes];
strm.avail_in = [self length];
strm.total_out = 0;
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
if (inflateInit2(&strm, (15+32)) != Z_OK) return nil;
while (!done)
{
// Make sure we have enough room and reset the lengths.
if (strm.total_out >= [decompressed length])
[decompressed increaseLengthBy: half_length];
strm.next_out = [decompressed mutableBytes] + strm.total_out;
strm.avail_out = [decompressed length] - strm.total_out;
// Inflate another chunk.
status = inflate (&strm, Z_SYNC_FLUSH);
if (status == Z_STREAM_END) done = YES;
else if (status != Z_OK) break;
}
if (inflateEnd (&strm) != Z_OK) return nil;
// Set real length.
if (done)
{
[decompressed setLength: strm.total_out];
return [NSData dataWithData: decompressed];
}
else return nil;
}
- (NSData *)gzipDeflate
{
if ([self length] == 0) return self;
z_stream strm;
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
strm.total_out = 0;
strm.next_in=(Bytef *)[self bytes];
strm.avail_in = [self length];
// Compresssion Levels:
// Z_NO_COMPRESSION
// Z_BEST_SPEED
// Z_BEST_COMPRESSION
// Z_DEFAULT_COMPRESSION
if (deflateInit2(&strm, Z_DEFAULT_COMPRESSION, Z_DEFLATED, (15+16), 8, Z_DEFAULT_STRATEGY) != Z_OK) return nil;
NSMutableData *compressed = [NSMutableData dataWithLength:16384]; // 16K chunks for expansion
do {
if (strm.total_out >= [compressed length])
[compressed increaseLengthBy: 16384];
strm.next_out = [compressed mutableBytes] + strm.total_out;
strm.avail_out = [compressed length] - strm.total_out;
deflate(&strm, Z_FINISH);
} while (strm.avail_out == 0);
deflateEnd(&strm);
[compressed setLength: strm.total_out];
return [NSData dataWithData:compressed];
}
// --------------------------------CRC32-------------------------------
static const unsigned long crc32table[] =
{
0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,
0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,
0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f,
0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,
0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,
0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,
0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9,
0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad,
0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683,
0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7,
0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79,
0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,
0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21,
0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,
0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db,
0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
};
- (unsigned int)crc32
{
unsigned int crcval;
unsigned int x, y;
const void *bytes;
unsigned int max;
bytes = [self bytes];
max = [self length];
crcval = 0xffffffff;
for (x = 0, y = max; x < y; x++) {
crcval = ((crcval >> 8) & 0x00ffffff) ^ crc32table[(crcval ^ (*((unsigned char *)bytes + x))) & 0xff];
}
return crcval ^ 0xffffffff;
}
// Hash function, by [[DamienBob]]
#define HEComputeDigest(method) \
method##_CTX ctx; \
unsigned char digest[method##_DIGEST_LENGTH]; \
method##_Init(&ctx); \
method##_Update(&ctx, [self bytes], [self length]); \
method##_Final(digest, &ctx);
#define HEComputeDigestNSData(method) \
HEComputeDigest(method) \
return [NSData dataWithBytes:digest length:method##_DIGEST_LENGTH];
#define HEComputeDigestNSString(method) \
static char __HEHexDigits[] = "0123456789abcdef"; \
unsigned char digestString[2*method##_DIGEST_LENGTH];\
unsigned int i; \
HEComputeDigest(method) \
for(i=0; i<method##_DIGEST_LENGTH; i++) { \
digestString[2*i] = __HEHexDigits[digest[i] >> 4]; \
digestString[2*i+1] = __HEHexDigits[digest[i] & 0x0f];\
} \
return [NSString stringWithCString:(char *)digestString length:2*method##_DIGEST_LENGTH];
#define SHA1_CTX SHA_CTX
#define SHA1_DIGEST_LENGTH SHA_DIGEST_LENGTH
- (NSData*) md5Digest
{
HEComputeDigestNSData(MD5);
}
- (NSString*) md5DigestString
{
HEComputeDigestNSString(MD5);
}
- (NSData*) sha1Digest
{
HEComputeDigestNSData(SHA1);
}
- (NSString*) sha1DigestString
{
HEComputeDigestNSString(SHA1);
}
- (NSData*) ripemd160Digest
{
HEComputeDigestNSData(RIPEMD160);
}
- (NSString*) ripemd160DigestString
{
HEComputeDigestNSString(RIPEMD160);
}
@end
Appleの組み込みlibcompressionがiOS 9で利用可能になりました。NSDataを圧縮するためのcompression_encode_bufferの短い例を以下に示します。
@import Compression;
NSData *theData = [NSData dataWithContentsOfFile:[<some file> path]];
size_t theDataSize = [theData length];
const uint8_t *buf = (const uint8_t *)[theData bytes];
uint8_t *destBuf = malloc(sizeof(uint8_t) * theDataSize);
size_t compressedSize = compression_encode_buffer(destBuf, theDataSize, buf, theDataSize, NULL, COMPRESSION_LZFSE);
self.<NSData item> = [NSData dataWithBytes:destBuf length:compressedSize];
NSLog(@"originalsize:%zu compressed:%zu", theDataSize, compressedSize);
free(destBuf);
多くの異なるアルゴリズムが利用可能です：
- LZMA
- LZ4
- ZLIB
- LZFSE
ブロック圧縮またはストリーム圧縮の両方がサポートされています。
https://developer.Apple.com/library/mac/documentation/Performance/Reference/Compression/ を参照してください
圧縮データしかなく、圧縮されていないサイズがわかっている場合は、以下を使用できます。
#import "zlib.h"
int datal = [zipedData length];
Bytef *buffer[uncompressedSize];
Bytef *dataa[datal];
[zipedData getBytes:dataa];
Long *ld;
uLong sl = datal;
*ld = uncompressedSize;
if(uncompress(buffer, ld, dataa, sl) == Z_OK)
{
NSData *uncompressedData = [NSData dataWithBytes:buffer length:uncompressedSize];
NSString *txtFile = [[NSString alloc] initWithData:uncompressedData encoding:NSUTF8StringEncoding];
}
zlib は電話で利用できると思います。
zipArchiveを使用するのが最善の選択だと私に信じてください： AES-256暗号化Zipファイルを解凍する方法？
必要に応じてサポートの準備ができています。
Objective-Zip は別のオプションです。これらの優れた 手順 を参照してください。
注意：XCode-> Edit-> Refactor-> Convert to Objective C ARCを使用して、ARCを使用するようにソースコードを変換する必要がありました。
NSURLはそれがgzipエンコードをサポートしていると言っているので、RESTful Webサービスが適切なときにgzipエンコードされたコンテンツを返す以外に何もする必要はありません。すべてのデコードは内部で行われます。