Few Useful Objective-C Snippets for an iOS App

LAUNCH MAIL AND SEND AN EMAIL

[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"mailto://mymail@myserver.com"]];

PREVENT SLEEP MODE

[UIApplication sharedApplication].idleTimerDisabled = YES;

STOP RESPONDING TO TOUCHES

[[UIApplication sharedApplication] beginIgnoringInteractionEvents];

RESUME RESPONDING TO TOUCHES

[[UIApplication sharedApplication] endIgnoringInteractionEvents];

DISPLAY AN ALERT WINDOW

UIAlertView* alert = [[[UIAlertView alloc] initWithTitle:@"Warning" message:@"too many alerts" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil] autorelease];
[alert show]

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Delay Code in iOS

double delayInSeconds = 6.0; 
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC); dispatch_after(popTime, dispatch_get_main_queue(), ^(void){ 
// unhide views, animate if desired
 [self.navigationController popViewControllerAnimated:YES]; 
});

Sliding Up UITextFields which are hidden by the keyboard in iOS

First, declare the following constants somewhere at the top of the view controller's implementation file. 


CGFloat animatedDistance;

static const CGFloat KEYBOARD_ANIMATION_DURATION = 0.3;

static const CGFloat MINIMUM_SCROLL_FRACTION = 0.2;

static const CGFloat MAXIMUM_SCROLL_FRACTION = 0.8;

static const CGFloat PORTRAIT_KEYBOARD_HEIGHT = 216;

static const CGFloat LANDSCAPE_KEYBOARD_HEIGHT = 162;


When the textfield will be touched, we will get the rect of the textfield and convert everything to the window coordinates.

Then we calculate the fraction between the top and bottom of the middle section for the text field's midline.

Then we will clamp this fraction so that the top section is all "0.0" and the bottom section is all "1.0".

Then this fraction is converted to scroll according to the keyboards height.

Finally, apply the animation.

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Hide the keyboard when you touch outside of an UITextField in iOS

On viewDidLoad add the following lines:

UITapGestureRecognizer *gestureRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(hideKeyboard)];
[self.view addGestureRecognizer:gestureRecognizer];


Then add the following function somewhere in the implementation file.

- (void) hideKeyboard {
[activeField resignFirstResponder];
}

Here activeField is an UITextField object. Declare it somewhere at the top of the view controller's implementation file.

How to Access Web Sites When They’re Down

When sites go down, there are actually a few ways to access them through the magic of caches and archives.

 

Access Cached Pages Through Google

Google caches a large portion of the internet, and it’s easy to access those caches when a site isn’t available. All you have to do is search for a URL prepended with “cache:” like this:

cache:http://sanzar-adnan.blogspot.com/

 

That’ll take you to the cached version of sanzar-adnan.blogspot.com. You can replace it with any URL to get the latest version Google currently has in its cache. 

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iPhone Application Development Tutorial

This is a free tutorial by the Stanford University.

download part-1

download part-2

Create Multiple Folders And Sub-Folders Easily In One Go

Using Batch (BAT) Command

The First method for creating multiple folders requires using the Batch (BAT) file. First you create a root folder in which you want your other folders to appear. Once done, create a text file in root folder and enter the md command in following way.

md <folder name>/<sub-folder name>

For example,

md Music
md Videos
md Pictures
md Documents
md C:\User\Test\Desktop\AddictiveTips\Documents\Home

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