KeyBoard, ScrollView,Scroll Offset,Validation

5.1  How to customize key board as per the requirement

        

            We can customize key pad as per the user requirements. The key pad type may be Number type,  URL ,Phone pad, Email- Address. If the user wants to enter e-mail id in particular text field, then the developer can set E-mail address type as key board. Following example shows key board type settings in iPhone application.

           

         Developer's can set the key pad via coding as well as attribute window. “setKeyboardType”

is the key to set key board type for particular text field. The following figure shows the key board type changing via attribute window,

         Also we can use textField Delegates method to handle the events in textField. We have to use UITextFieldDelegate in the header section to use the textField delegates in our application. Also connect the delegate's of TextField in to file's owner or set the delegate file for particular textField via coding as follows, [textField setDelegate:self]. Following are the list of textField delegates available in iPhone application development,

 - (BOOL)textFieldShouldBeginEditing:(UITextField *)textField;      // return NO to disallow editing.

 - (void)textFieldDidBeginEditing:(UITextField *)textField;              // became first responder

 - (BOOL)textFieldShouldEndEditing:(UITextField *)textField;       // return YES to allow editing to  stop and to resign first responder status. NO to disallow the editing session to end

 - (void)textFieldDidEndEditing:(UITextField *)textField;                // may be called if forced even if shouldEndEditing returns NO (e.g. view removed from window) or endEditing:YES called

 - (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string;                                           // return NO to not change text

 - (BOOL)textFieldShouldClear:(UITextField *)textField;               // called when clear button pressed. return NO to ignore (no notifications)

 - (BOOL)textFieldShouldReturn:(UITextField *)textField;              // called when 'return' key pressed. return NO to ignore.

5.2  Implementation of scrollview with example

         ScrollView is an object which is used in iPhone application to show more amount of data in a single view on the basis of scrolling. If the developer need to present more information in a single view, then he can make use of scroll view in his application.

         Now, we shall see a view-based application to implement scrollView. As usual, starts with Xcode and create a view based application. In the header file, add UIScrollView object and one UIView object. After adding those objects, the header file will be looking like as follows.

         In the implementation section, we have to write coding in ViewDidLoad function. Before that, first we have to connect the outlets in xib files. Set UIView size as 320*650 and come back to implementation section. Now, set the scrollView content size as view size and add the view as sub view for the scroll view via coding in viewDidLoad function. Implementation file coding will be as follows,

        

         Now come again to xib file and you can set properties to scroll view in it's attribute window.

Add some text fields in the view and build and run the application, output will be as follows,

        

        

4.3  Text view and its delegates

         If the developer wants to use multi lined text field, then he should use Text view for that purpose. Text view can be used to display or get a certain amount of text data. Text view it self having its own scroll and edit functionality. We can also customize own text view by changing its attribute values in attribute window.

         Similar to text field, text view also having it's own delegate functions. To use the text view delegate , we have to add UITextViewDelegate in the header file. Resigning key pad coding is not similar to text field, we have to write our own coding for resigning a key pad in text view delegates.

        

         Now we shall see an example for text view and its delegate. First create a view based application in Xcode and come to its header file. Add text view delegate and object in the header section, the code will be look as follows,

         Now we have to come back in the implementation section. To resign the kay board, write the codings in the delegate file such as,

-      (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text

         Now we have to connect the outlet and delegate of text view in the xib file. First drag and drop UITextView  from the object pane and connect its delegate in the files owner.  Build and run the application, finally we will get the output as follows,

         Apart from this delegate, text view also having delegates such as,

        

4.4  A simple Login Validation

         Now we shall see a simple Login validation program for iPhone. We can use a view based application for this program.

         In this application, we are going to validate user name, password and confirm password and email id. First you have to start with Xcode and create a view based application. Come to header file and Add textfield delegate and UITextField outlets for user name, email id and passwords.

The header file will be look as follows,

        

        

         isValidate is the method used for validation purpose and  “done” is used to call the validation function. IsValidateEmail is used for email validation purpose.

         Now we have to write codes in the implementation section. We have define the functions in implementation file. First we have to define isValidateEmail and it will be like as follows,

         Just use the above code as standard validation for email-id. After that we have to define isValidate function. IsValidate function will be as follows,

         In this function, first we have to define two variables namely error and message for easy access and efficiency. After that we have to check whether  all the fields are entered and make sure that none of the fields are empty, for that purpose we check all the fields are filled or not. If  any field is empty, alert with error message is pop upped.

         Once the fields are filled, we have to check whether passwords are matched or not, finally we have to check whether the email id is valid or not. For that purpose, call isValidEmail function by using [self  isValidEmail:tfEmail.text] command.

         Finally define the done action to call the validate function and the done action coding is look as follows,

         Thats all we have to do in the coding section. Now come to xib file and connect the outlets and actions. Set password and confirm password  text field as secure one by enable the secure property in TextField attribute window.

         In attribute window for Text Fields, set place holder for each text field in the xib and finally build and run the application, the output will be as follows,