eMail Validation in iOS sdk

NSString *email = @"examle@example.com";

    NSString *emailRegEx =

    @"(?:[a-z0-9!#$%\\&'*+/=?\\^_`{|}~-]+(?:\\.[a-z0-9!#$%\\&'*+/=?\\^_`{|}"

    @"~-]+)*|\"(?:[\\x01-\\x08\\x0b\\x0c\\x0e-\\x1f\\x21\\x23-\\x5b\\x5d-\\"

    @"x7f]|\\\\[\\x01-\\x09\\x0b\\x0c\\x0e-\\x7f])*\")@(?:(?:[a-z0-9](?:[a-"

    @"z0-9-]*[a-z0-9])?\\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|\\[(?:(?:25[0-5"

    @"]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-"

    @"9][0-9]?|[a-z0-9-]*[a-z0-9]:(?:[\\x01-\\x08\\x0b\\x0c\\x0e-\\x1f\\x21"

    @"-\\x5a\\x53-\\x7f]|\\\\[\\x01-\\x09\\x0b\\x0c\\x0e-\\x7f])+)\\])";

    

    NSPredicate *regExPredicate =

    [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailRegEx];

    BOOL myStringMatchesRegEx = [regExPredicate evaluateWithObject:email];

    

    

    if(!myStringMatchesRegEx)

    {

        UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"email" message:@"Email id is invalid, please provide a valid email id." delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];

        [alert show];

        [alert release];

    }

    else

        NSLog(@"Valid eMail address");

Zip-Unzip in ios, iPhone, iPad,mac-osX

An Very good library to zip/uzip files using objective-c.
You can also unzip password protected file using this utility.
steps to use...
1)Download it from http://code.google.com/p/ziparchive/
2)include minizip folder and ZipArchive.h and ZipArchive.m files into your project.
3) import ZipArchive.h in your class and then call approprite methods of ZipArchive to zip/unzip.

for example:
//to create zipfile
 -(BOOL) CreateZipFile2:(NSString*) zipFile;
//to create password protected zipfile

-(BOOL) CreateZipFile2:(NSString*) zipFile Password:(NSString*) password;

////to addFile To zipfile

-(BOOL) addFileToZip:(NSString*) file newname:(NSString*) newname;

//closing zip

-(BOOL) CloseZipFile2;

//unziping zip file

-(BOOL) UnzipOpenFile:(NSString*) zipFile;

//unzip password protected zip file

-(BOOL) UnzipOpenFile:(NSString*) zipFile Password:(NSString*) password;

-(BOOL) UnzipFileTo:(NSString*) path overWrite:(BOOL) overwrite;

-(BOOL) UnzipCloseFile;

//Demo code.

//Unziping File

    ZipArchive* zipArchive = [[ZipArchive alloc] init];

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,

                                                         NSUserDomainMask,

                                                         YES);

    

    NSString *zipFile = [[paths lastObject] stringByAppendingPathComponent:@"abcd.zip"];

    NSString *extractedFile = [[paths lastObject] stringByAppendingPathComponent:@"Extracted"];

    if( [zipArchive UnzipOpenFile: zipFile Password:@"mypassword"] )

    {

        BOOL ret = [zipArchive UnzipFileTo:extractedFile overWrite:YES];

        if( NO==ret )

        {

            UIAlertView *alert=[[UIAlertView alloc] initWithTitle:@"Error" message:[NSString stringWithFormat:@"Unable to unzip."] delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];

            [alert show];

            [alert release];

            [zipArchive release];

            return false;

        }

        [zipArchive UnzipCloseFile];