check that a string is numeric only with limit in UITextField.----- IOS

-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    /* for backspace */
    if([string length]==0){
        return YES;
    }
   
    /*  limit to only numeric characters  */
   
    NSCharacterSet *myCharSet = [NSCharacterSet characterSetWithCharactersInString:@"0123456789"];
    for (int i = 0; i < [string length]; i++) {
        unichar c = [string characterAtIndex:i];
        if ([myCharSet characterIsMember:c]) {
            NSUInteger newLength = [textField.text length] + [string length] - range.length;
            return (newLength > 8 ) ? NO : YES;

        }
    }
   
    return NO;
}

validate Email Using Regex-- ios sdk

-(BOOL) NSStringIsValidEmail:(NSString *)checkString
{
   BOOL stricterFilter = YES; // Discussion http://blog.logichigh.com/2010/09/02/validating-an-e-mail-address/
   NSString *stricterFilterString = @"[A-Z0-9a-z\\._%+-]+@([A-Za-z0-9-]+\\.)+[A-Za-z]{2,4}";
   NSString *laxString = @".+@([A-Za-z0-9]+\\.)+[A-Za-z]{2}[A-Za-z]*";
   NSString *emailRegex = stricterFilter ? stricterFilterString : laxString;
   NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailRegex];
   return [emailTest evaluateWithObject:checkString];
}

Set Char Input Limit to UITextfield in iPhone -- IOS SDK

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
  
NSUInteger newLength = [textField.text length] + [string length] - range.length;
    return (newLength > 30) ? NO : YES;

}

UK Postal code Validation using regex -- iOS

- (BOOL) validateUKPostalCode: (NSString *) code {

  

    NSString *ukcodeRegex = @"(GIR 0AA)|((([A-Z-[QVX]][0-9][0-9]?)|(([A-Z-[QVX]][A-Z-[IJZ]][0-9][0-9]?)|(([A-Z-[QVX]][0-9][A-HJKSTUW])|([A-Z-[QVX]][A-Z-[IJZ]][0-9][ABEHMNPRVWXY])))) [0-9][A-Z-[CIKMOV]]{2})";

    NSPredicate *codeTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", ukcodeRegex];

    

    return [codeTest evaluateWithObject: code];

}

Google Analytics Integration in ios ---- IOS SDK

Google Analytics, Create a new profile
You can download it from: http://code.google.com/apis/analytics/docs/tracking/mobileAppsTracking.html.

Step 1: Add a new websites profile.

Step 2: Select Add a Profile for a new domain.
Step 3: Enter URL (no need to be a live URL, e.g.: testapp.articledean.com). Google never uses this URL; this entry is just for our reference, so a meaningful URL will do.
Step 4: Select the Country and TimeZone.
Step 5: Click Finish, and Google Analytics will give you a Web Property ID that starts with UA. Note it down; this is the unique identification of your application. This ID looks like: Web Property ID: UA-12345678-2 (Sample ID).

Download and Integrate the Google Analytics Library for iPhone Applications
Download link: Analytics SDK for iPhone.
Download and extract the library. The following two files are the key components of the Google Analytics Library.
    1.    GANTracker.h
    2.    libGoogleAnalytics.a
Copy the above files into the library folder of you iPhone application in XCode. Make sure that you are copying the files into the destination folder.

Google Analytics Library requires "CFNetwork" and "libsqlite3.0.dylib
Using the Google Analytics Library in code
Import the "GANTracker.h" file into your application delegate class. In the "applicationDidFinishLaunching()" method, initialize the tracker object.
#import "GANTracker.h"
[[GANTracker sharedTracker] startTrackerWithAccountID:@"UA-12345678-2"
                               dispatchPeriod:20
                               delegate:nil];
Google Analytics supports two levels of tracking: "PageViews" and "Events". "Page Views" are like tracking regular web pages."Events" tracking can be used on button clicks, radio button selections, text box entries etc.

Page Views sample code in the applicationDidFinishLaunching method
NSError *error;
if (![[GANTracker sTracker] trackPageview:@"/applicationlaunched"
                                        withError:&err]) {
     // Error Handling
   }
Events sample code, when an event fires (like button click)
- (IBAction) clickMe:(id) sender
{
        NSError *err;
        if (![[GANTracker sTracker] trackEvent:@"clkButton"
                                            action:@"trackMyPage"
                                            label:@"sampleLabel"
                                            value:-1
                                        withError:&err]) {
               // Error Handling

        }
}
    •    "clkButton" is a group that represents a Button Click Event category. You can track all your button clicks by using this user defined group.
    •    "trackMyPage" is the event name when my button is clicked; I will call the "trackMyPage" event method.
    •    "sampleLabel" is just a label that gives you information about your tracking.

Get count of row Selected in UITableView -- IOS

Create NSmutalble Array in your .h file -
NSMutableArray *SelectedRowCountArr;

in .m File :-
- (void)viewDidLoad
{
       SelectedRowCountArr = [[NSMutableArray alloc]init];
   }

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
 if(![SelectedRowCountArr containsObject:indexPath])
    {
        [SelectedRowCountArr addObject:indexPath];

    }else{
    [SelectedRowCountArr removeObject:indexPath];

    }

    NSLog(@"SelectedRowCountArr.count...%d",SelectedRowCountArr.count);
}

Saving Data in the keychain ---- iphone sdk

 Keychain to store usernames and passwords, and since it's stored securely and only accessible to your app

Download Sample code from Apple website sample code 

Add Security.framework 

Add KeychainItemWrapper .h & .m files into your project

 #import the .h file wherever you need to use keychain and then create an instance of this class:

KeychainItemWrapper *keychainItem = [[KeychainItemWrapper alloc] initWithIdentifier:@"AppLoginItems" accessGroup:nil];

(AppLoginItems can be anything you choose to call your Keychain item and you can have multiple items if required)

Then you can set the username and password using:

[keychainItem setObject:@"password you are saving" forKey:kSecValueData];

[keychainItem setObject:@"username you are saving" forKey:kSecAttrAccount];

Get them using:

NSString *password = [keychainItem objectForKey:kSecValueData];

NSString *username = [keychainItem objectForKey:kSecAttrAccount];

Or delete them using:

[keychainItem resetKeychainItem];