Tuesday, 29 March 2011

UIAlert View

Display an AlertView on Button Touch

In this post i will be explaining how to display your name in an alert view.

Alert view: An alert view is like a message box in which you give notifications to the user regarding any particular error or any sort of message that you want.

So here's my basic view

Now all i want to display here is the text of the Textfield in my alert view, so i will go step wise here.

Step 1: Open Xcode and create a window based application and give it an appropriate name, i have given it AlertDemo
Step 2: Create a class of UIViewController type and create objects of label, button and a text field also we will require a function where we will write the code to display an Alert view, heres what the Myviewcontroller.h file looks like this

@interface Myviewcontroller : UIViewController {
UILabel *lbl;
UIButton *btn;
UITextField *txtfield;
-(void)buttonTouch; //function which will display alert view on button touch

now coming to the Myviewcontroller.m file where we will initialize these objects and give logic to our view, the init method will look like this

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
if (self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]) {
// Custom initialization
//setting the label
lbl = [[UILabel alloc]initWithFrame:CGRectMake(33, 101, 49, 21)];
lbl.text = @"Name";
//setting the button
btn = [UIButton buttonWithType:UIButtonTypeRoundedRect];
[btn setFrame:CGRectMake(119, 140, 72, 37)];//setting the frame
[btn setTitle:@"Touch" forState:UIControlStateNormal]; //setting the text and state of button

[btn addTarget:self action:@selector(buttonTouch) forControlEvents:UIControlEventTouchUpInside]; //calling the function
//setting the text
txtfield = [[UITextField alloc]initWithFrame:CGRectMake(90, 101, 130, 31)];
[txtfield setBorderStyle:UITextBorderStyleRoundedRect];
return self;

setting the buttonTouch method

UIAlertView *objalert = [[UIAlertView alloc]initWithTitle:@"Alert box demo" message:txtfield.text delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:@"Cancel",nil];
[objalert show];

In the above code what i have done is created the object of UIAlertview, so now lets have a look at its parameters

1. initWithTitle: String that appears as the title of the message.
2.message: The initial message that you want to show to the user.
3. delegate: If you have specified some delegate to the alertview then set self else set it to nil.
4. cancelButtonTitle: The title of the cancel button else you can write nil if no cancel button.
5. otherButtonTitles: The title of another button.

Finally you write a nil in order to specify that their are no more button to be added to the alert view

now coming to the function called loadView,

- (void)loadView {
[super loadView];
[self.view addSubview:btn];
[self.view addSubview:txtfield];
[self.view addSubview:lbl];

Now we will go into the app delegate.m file and add the view to our window

#import "AlertDemoAppDelegate.h"
#import "Myviewcontroller.h"

@implementation AlertDemoAppDelegate

@synthesize window;

- (void)applicationDidFinishLaunching:(UIApplication *)application {

// Override point for customization after application launch
Myviewcontroller * obj = [[Myviewcontroller alloc]init];
[window addSubview:obj.view];
[window makeKeyAndVisible];

now after that you can touch the button and after that you can see the following result on the iPhone simulator.

BitCode hopes that this post has helped you in clearing your concepts regarding the view and view controllers. You can post your queries at bitcode.pune@gmail.com for any technical assistance.

1 comment:

  1. Nice and a simple tutorial. Thank you Ravi sir.