iPhone压缩与解压

 

1.内存中解压NSData:

-(NSData *)uncompressZippedData:(NSData *)compressedData { if ([compressedData length] == 0) return compressedData; unsigned full_length = [compressedData length]; unsigned half_length = [compressedData length] / 2; NSMutableData *decompressed = [NSMutableData dataWithLength: full_length + half_length]; BOOL done = NO; int status; z_stream strm; strm.next_in = (Bytef *)[compressedData bytes]; strm.avail_in = [compressedData 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; } }

 

2.使用minizip库解压单个文件:

#define CHUNK 16384 -(void)uncompress:(NSString *)zippath free:(NSString *)freepath { gzFile file = gzopen([zippath UTF8String], "rb"); FILE *dest = fopen([freepath UTF8String], "w"); unsigned char buffer[CHUNK]; int uncompressedLength = gzread(file, buffer, CHUNK); if(fwrite(buffer, 1, uncompressedLength, dest) != uncompressedLength || ferror(dest)) { NSLog(@"error writing data"); } fclose(dest); gzclose(file); }