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1. 导入libz库(如:libz 1.2.5.dylib)
2. 引入头文件
#import "zlib.h"3. 实现解压(输入输出都为NSData对象)
-(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];
}
// chadeltu 加了(Bytef *)
strm.next_out = (Bytef *)[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;
}
}使用样例:
// gzip解压,mapFilePath为待解压文件路径
NSData *dataInitial = [NSData dataWithContentsOfFile:mapFilePath]; // 解压前
NSData *dataUncompressed = [self uncompressZippedData:dataInitial]; // 解压后参考博客:
在iPhone开发中实现解压缩gzip
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