iOS 字符串压缩和解压缩

实现对字符串进行压缩和解压缩操作 前提需要导入libz.1.2.5.dylib 库

import "BYViewController.h"

#import "zipAndUnzip.h"
 
@interface BYViewController ()
 
@end
 
@implementation BYViewController
 
- (void)viewDidLoad
{undefined
    [super viewDidLoad];
   
 zipAndUnzip *zipAnd = [[zipAndUnzip alloc] init];
    
    NSString *str = @"Hello.madison向显笑";
    NSStringEncoding enc = CFStringConvertEncodingToNSStringEncoding(NSUTF16BigEndianStringEncoding);
    NSData *data = [str dataUsingEncoding:enc];
    NSData *dataDeflate = [zipAnd gzipDeflate:data];
    Byte *byte = (Byte *)[dataDeflate bytes];
 
    for (int i=0 ; i<[dataDeflate length]; i++){undefined
    
        NSLog(@"byte = %d",byte[i]);
    }
    
    NSData *adata = [[NSData alloc] initWithBytes:byte length:[dataDeflate length]];
//    NSData *dataInflate =  [zipAnd gzipInflate:adata];
    NSString *aString = [[NSString alloc] initWithData:adata encoding:enc];
    NSLog(@"aString:%@",aString);
 
}
 
@end





@interface zipAndUnzip : NSObject
 
- (NSData *)gzipInflate:(NSData*)data;
- (NSData *)gzipDeflate:(NSData*)data;
 
@end


#import "zipAndUnzip.h"
#import "zlib.h"
 
@implementation zipAndUnzip
 
//解压缩
  • (NSData )gzipInflate:(NSData)data
    {
    if ([data length] == 0) return data;

    unsigned full_length = (int)[data length];
    unsigned half_length = (int)[data length] / 2;

    NSMutableData *decompressed = [NSMutableData dataWithLength: full_length + half_length];
    BOOL done = NO;
    int status;

    z_stream strm;
    strm.next_in = (Bytef *)[data bytes];
    strm.avail_in = (int)[data 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 = (uint)[decompressed length] - (uint)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;
    }

//压缩

  • (NSData )gzipDeflate:(NSData)data
    {
    if ([data length] == 0) return data;

    z_stream strm;

    strm.zalloc = Z_NULL;
    strm.zfree = Z_NULL;
    strm.opaque = Z_NULL;
    strm.total_out = 0;
    strm.next_in=(Bytef *)[data bytes];
    strm.avail_in = (int)[data 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 = (uInt)[compressed length] - (uint)strm.total_out;
      
      deflate(&strm, Z_FINISH);
    

    } while (strm.avail_out == 0);

    deflateEnd(&strm);

    [compressed setLength: strm.total_out];
    return [NSData dataWithData:compressed];
    }

原文链接:https://blog.csdn.net/u011043997/article/details/25381699

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