console output stating bit length overflow

When I run my app I get this output to the console:

bit length overflow code 11 bits 7->5 code 16 bits 4->5

bit length overflow code 4 bits 6->7

bit length overflow code 3 bits 6->7 code 0 bits 6->7

bit length overflow code 16 bits 4->5

bit length overflow code 4 bits 6->7 code 5 bits 6->5 code 16 bits 4->5

bit length overflow code 16 bits 4->5

bit length overflow code 0 bits 6->7

bit length overflow code 11 bits 6->7

The app zips up 3 files and saves it to its documents folder and all seems OK....apart from this output.

UPDATED:

NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; 

@try { 
    NSString *docsPath =[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
    NSString *filePath = [docsPath stringByAppendingPathComponent:@"ZipTest.zip"]; 
    ZipFile *zipFile = [[ZipFile alloc] initWithFileName:filePath mode:ZipFileModeCreate]; 
    ZipWriteStream *stream; 

    if (self.textSwitch.on) { 
        stream = [zipFile writeFileInZipWithName:@"text.txt" compressionLevel:开发者_JAVA技巧ZipCompressionLevelBest];
    } 
    [zipFile close]; 
    [zipFile release]; 
} 
@catch (ZipException *ze) {} 
@catch (id e) {} 

[pool drain];

What does it mean?

Thanks

According to this Mozilla bugthese are caused by building ZLIB in debug mode and are harmless.. You could look into always building a release version of ZLIB.