iOS/MAC 数据压缩与解压缩及常用算法 LZMA、ZLIB
苹果提供的常用的数据压缩算法LZMA、ZLIB、LZ4等;
这三种算法也是苹果建议的,可跨平台使用;
定义如下:
/* Commonly-available encoders */ COMPRESSION_LZ4 = 0x100, // available starting OS X 10.11, iOS 9.0 COMPRESSION_ZLIB = 0x205, // available starting OS X 10.11, iOS 9.0 COMPRESSION_LZMA = 0x306, // available starting OS X 10.11, iOS 9.0 COMPRESSION_LZ4_RAW = 0x101, // available starting OS X 10.11, iOS 9.0 /* Apple-specific encoders */ COMPRESSION_LZFSE = 0x801, // available starting OS X 10.11, iOS 9.0
适用于有大文件数据上传下载,节省流量可以考虑使用;
使用说明:
1. 需要引用头文件
#include "compression.h"
2. 数据压缩示例:
- (void)testCompress{ NSData *src = [NSData dataWithContentsOfFile:@"/Users/cocoajin/Desktop/src.txt"]; NSLog(@"src: %ld",src.length); uint8_t *dstBuffer = (uint8_t *)malloc(src.length); memset(dstBuffer, 0, src.length); size_t compressResultLength = compression_encode_buffer(dstBuffer, src.length, [src bytes], src.length, NULL, COMPRESSION_LZMA); if (compressResultLength > 0) { NSData *newData = [NSData dataWithBytes:dstBuffer length:compressResultLength]; [newData writeToFile:@"/Users/cocoajin/Desktop/compress.data" atomically:YES]; NSLog(@"com: %ld",compressResultLength); NSLog(@"com: %.2f",(src.length-compressResultLength)/(float)src.length); }else{ NSLog(@"compress error!"); } free(dstBuffer); }
3. 数据解压缩示例:
- (void)testDeCompress{ NSData *src = [NSData dataWithContentsOfFile:@"/Users/cocoajin/Desktop/compress.data"]; NSLog(@"src: %ld",src.length); uint8_t *dstBuffer = (uint8_t *)malloc(1024*1024*10); memset(dstBuffer, 0, src.length); size_t decompressLen = compression_decode_buffer(dstBuffer,1024*1024*10,src.bytes,src.length,NULL,COMPRESSION_LZMA); if (decompressLen > 0) { NSData *newData = [NSData dataWithBytes:dstBuffer length:decompressLen]; [newData writeToFile:@"/Users/cocoajin/Desktop/decompress.txt" atomically:YES]; NSLog(@"com: %ld",decompressLen); }else{ NSLog(@"decompressLen error!"); } free(dstBuffer); }
4. 实际测对一个1.9M的txt小说文件压缩,压缩以后大小为0.8m,压缩效果还是很明显的;