added two methods for append zip file

Author: V01dZer0

ZipArchive.h

@@ -95,7 +95,9 @@ typedef void(^ZipArchiveProgressUpdateBlock)(int percentage, int filesProcessed,
 -(id) initWithFileManager:(NSFileManager*) fileManager;
 
 -(BOOL) CreateZipFile2:(NSString*) zipFile;
+-(BOOL) CreateZipFile2:(NSString*) zipFile append:(BOOL)isAppend;
 -(BOOL) CreateZipFile2:(NSString*) zipFile Password:(NSString*) password;
+-(BOOL) CreateZipFile2:(NSString*) zipFile Password:(NSString*) password append:(BOOL)isAppend;
 -(BOOL) addFileToZip:(NSString*) file newname:(NSString*) newname;
 -(BOOL) addDataToZip:(NSData*) data fileAttributes:(NSDictionary *)attr newname:(NSString*) newname;
 -(BOOL) CloseZipFile2;
@@ -105,6 +107,10 @@ typedef void(^ZipArchiveProgressUpdateBlock)(int percentage, int filesProcessed,
 -(BOOL) UnzipFileTo:(NSString*) path overWrite:(BOOL) overwrite;
 -(NSDictionary *)UnzipFileToMemory;
 -(BOOL) UnzipCloseFile;
--(NSArray*) getZipFileContents;     // list the contents of the zip archive. must be called after UnzipOpenFile
+
+// List the contents of the zip archive. must be called after UnzipOpenFile.
+// If zip file was appended with `CreateZipFile2:append:` or ``CreateZipFile2:Password:append:`,
+// `getZipFileContents` result won't be updated until re-unzip-open after close write handle (`CloseZipFile2` then `UnzipCloseFile` then (`UnzipOpenFile:` or `UnzipOpenFile:Password`) get called).
+-(NSArray*) getZipFileContents;
 
 @end

ZipArchive.m

@@ -77,7 +77,12 @@ -(void) dealloc
 
 -(BOOL) CreateZipFile2:(NSString*) zipFile
 {
-	_zipFile = zipOpen( (const char*)[zipFile UTF8String], 0 );
+    return [self CreateZipFile2:zipFile append:NO];
+}
+
+-(BOOL) CreateZipFile2:(NSString*) zipFile append:(BOOL)isAppend
+{
+    _zipFile = zipOpen( (const char*)[zipFile UTF8String], (isAppend ? APPEND_STATUS_ADDINZIP : APPEND_STATUS_CREATE) );
 	if( !_zipFile ) 
 		return NO;
 	return YES;
@@ -97,6 +102,12 @@ -(BOOL) CreateZipFile2:(NSString*) zipFile Password:(NSString*) password
 	return [self CreateZipFile2:zipFile];
 }
 
+-(BOOL) CreateZipFile2:(NSString*) zipFile Password:(NSString*) password append:(BOOL)isAppend
+{
+    self.password = password;
+    return [self CreateZipFile2:zipFile append:isAppend];
+}
+
 /**
  * add an existing file on disk to the zip archive, compressing it.
  *