Read and Write Array, Dictionary and Other Collections to Files

http://iosdevelopertips.com/data-file-management/read-and-write-array-dictionary-and-other-collections-to-files.html

With just a few lines of code, you can read/write collections to/from files. The code below shows examples for writing and reading back both arrays and dictionaries.

Read and Write Collections to File

NSArray *array = [NSArray arrayWithObjects: 
    @"Hefeweizen", @"IPA", @"Pilsner", @"Stout", nil];

NSDictionary *dictionary = [NSDictionary dictionaryWithObjectsAndKeys:
  array, @"array", @"Stout", @"dark", @"Hefeweizen", @"wheat", @"IPA", 
  @"hoppy", nil];

// Get path to documents directory
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, 
  NSUserDomainMask, YES);
if ([paths count] > 0)
{
  // Path to save array data
  NSString  *arrayPath = [[paths objectAtIndex:0] 
      stringByAppendingPathComponent:@"array.out"];

  // Path to save dictionary
  NSString  *dictPath = [[paths objectAtIndex:0] 
      stringByAppendingPathComponent:@"dict.out"];

  // Write array
  [array writeToFile:arrayPath atomically:YES];

  // Write dictionary
  [dictionary writeToFile:dictPath atomically:YES];

  // Read both back in new collections
  NSArray *arrayFromFile = [NSArray arrayWithContentsOfFile:arrayPath];
  NSDictionary *dictFromFile = [NSDictionary dictionaryWithContentsOfFile:dictPath];

  for (NSString *element in arrayFromFile) 
    NSLog(@"Beer: %@", element);

  for (NSString *key in dictFromFile) 
    NSLog(@"%@ Style: %@", key, [dictionary valueForKey:key]); 
}

NSArray *array = [NSArray arrayWithObjects:

@"Hefeweizen", @"IPA", @"Pilsner", @"Stout", nil];

NSDictionary *dictionary = [NSDictionary dictionaryWithObjectsAndKeys:

array, @"array", @"Stout", @"dark", @"Hefeweizen", @"wheat", @"IPA",

@"hoppy", nil];

// Get path to documents directory

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,

NSUserDomainMask, YES);

if ([paths count] > 0)

{

// Path to save array data

NSString *arrayPath = [[paths objectAtIndex:0]

stringByAppendingPathComponent:@"array.out"];

// Path to save dictionary

NSString *dictPath = [[paths objectAtIndex:0]

stringByAppendingPathComponent:@"dict.out"];

// Write array

[array writeToFile:arrayPath atomically:YES];

// Write dictionary

[dictionary writeToFile:dictPath atomically:YES];

// Read both back in new collections

NSArray *arrayFromFile = [NSArray arrayWithContentsOfFile:arrayPath];

NSDictionary *dictFromFile = [NSDictionary dictionaryWithContentsOfFile:dictPath];

for (NSString *element in arrayFromFile)

NSLog(@"Beer: %@", element);

for (NSString *key in dictFromFile)

NSLog(@"%@ Style: %@", key, [dictionary valueForKey:key]);

}

Write/Read data to .plist file

http://ipgames.wordpress.com/tutorials/writeread-data-to-plist-file/

First of all add a plist to your project in Xcode. For example “data.plist”.
Next, look at this code which creates path to plist in documents directory:

NSError *error;

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); //1

NSString *documentsDirectory = [paths objectAtIndex:0]; //2

NSString *path = [documentsDirectory stringByAppendingPathComponent:@"data.plist"]; //3

NSFileManager *fileManager = [NSFileManager defaultManager];

if (![fileManager fileExistsAtPath: path]) //4

{

NSString *bundle = [[NSBundle mainBundle] pathForResource:@"data" ofType:@"plist"]; //5

[fileManager copyItemAtPath:bundle toPath: path error:&error]; //6

}

NSError *error;

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); //1

NSString *documentsDirectory = [paths objectAtIndex:0]; //2

NSString *path = [documentsDirectory stringByAppendingPathComponent:@"data.plist"]; //3

NSFileManager *fileManager = [NSFileManager defaultManager];

if (![fileManager fileExistsAtPath: path]) //4

{

NSString *bundle = [[NSBundle mainBundle] pathForResource:@"data" ofType:@"plist"]; //5

[fileManager copyItemAtPath:bundle toPath: path error:&error]; //6

}

1) Create a list of paths.
2) Get a path to your documents directory from the list.
3) Create a full file path.
4) Check if file exists.
5) Get a path to your plist created before in bundle directory (by Xcode).
6) Copy this plist to your documents directory.

Read data:

NSMutableDictionary *savedStock = [[NSMutableDictionary alloc] initWithContentsOfFile: path];

//load from savedStock example int value

int value;

value = [[savedStock objectForKey:@"value"] intValue];

[savedStock release];

NSMutableDictionary *savedStock = [[NSMutableDictionary alloc] initWithContentsOfFile: path];

//load from savedStock example int value

int value;

value = [[savedStock objectForKey:@"value"] intValue];

[savedStock release];

Write data:

NSMutableDictionary *data = [[NSMutableDictionary alloc] initWithContentsOfFile: path];

//here add elements to data file and write data to file

int value = 5;

[data setObject:[NSNumber numberWithInt:value] forKey:@"value"];

[data writeToFile: path atomically:YES];

[data release]

NSMutableDictionary *data = [[NSMutableDictionary alloc] initWithContentsOfFile: path];

//here add elements to data file and write data to file

int value = 5;

[data setObject:[NSNumber numberWithInt:value] forKey:@"value"];

[data writeToFile: path atomically:YES];

[data release]

Remember about two things:

1) You must create a plist file in your Xcode project.
2) To optimize your app, better is to save all the data when application (or for example view) is closing. For instance in applicationWillTerminate. But if you are storing really big data, sometimes it cannot be saved in this method, because the app takes too long to close and the system will terminate it immediately.

How to change Status Bar text color in iOS 7

No need to code. It can all be done from the plist:

(1) Set “View controller-based status bar appearance” to “NO”
(2) Set “Status bar style” to “Opaque black style“.

Raw values are:
UIViewControllerBasedStatusBarAppearance = NO
UIStatusBarStyle = UIStatusBarStyleBlackOpaque

http://stackoverflow.com/questions/17678881/how-to-change-status-bar-text-color-in-ios-7

Change the Back button Title in iOS UINavigation

In the calling controller (meaning, the parent controller where you will push the new controller), add this in viewdidload:

self.navigationItem.backBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"Custom Back Title"
style:UIBarButtonItemStyleBordered
target:nil
action:nil];

self.navigationItem.backBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"Custom Back Title"

style:UIBarButtonItemStyleBordered

target:nil

action:nil];

http://programming.mvergel.com/2012/11/change-back-button-title-in-ios.html#.UseyJXk9XfM

iOS7 – Stop views from going under the navigation bar or tab bar in your viewController

First check for iOS 7 then implement: self.edgesForExtendedLayout = UIRectEdgeNone;

    float systemVersion = [[[UIDevice currentDevice] systemVersion] floatValue];
    if (systemVersion >= 7.0)
    {
        self.edgesForExtendedLayout = UIRectEdgeNone;
    }

float systemVersion = [[[UIDevice currentDevice] systemVersion] floatValue];

if (systemVersion >= 7.0)

{

self.edgesForExtendedLayout = UIRectEdgeNone;

}

UIAlertView – a simple text input dialog box

Create the alertView with style UIAlertViewStylePlainTextInput:

UIAlertView * alert = [[UIAlertView alloc] initWithTitle:@"Hello!" message:@"Please enter your name:" delegate:self cancelButtonTitle:@"Continue" otherButtonTitles:nil];
alert.alertViewStyle = UIAlertViewStylePlainTextInput;
UITextField * alertTextField = [alert textFieldAtIndex:0];
alertTextField.keyboardType = UIKeyboardTypeNumberPad;
alertTextField.placeholder = @"Enter your name";
[alert show];

UIAlertView * alert = [[UIAlertView alloc] initWithTitle:@"Hello!" message:@"Please enter your name:" delegate:self cancelButtonTitle:@"Continue" otherButtonTitles:nil];

alert.alertViewStyle = UIAlertViewStylePlainTextInput;

UITextField * alertTextField = [alert textFieldAtIndex:0];

alertTextField.keyboardType = UIKeyboardTypeNumberPad;

alertTextField.placeholder = @"Enter your name";

[alert show];

This produces an alertView:

UIAlertView that uses the UIAlertViewPlainTextInput alertStyle to ask a user name

When pressing any buttons, the regular delegate methods will be called and you can extract the textInput there like so:

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex{ 
    NSLog(@"Entered: %@",[[alertView textFieldAtIndex:0] text]);
}

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex{

NSLog(@"Entered: %@",[[alertView textFieldAtIndex:0] text]);

}

View rotation methods

View rotation methods for iOS5 and iOS6

#pragma mark - View rotation methods

// iOS5 support
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{

    // Support portrait only orientation for iPhone iOS5
    if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad){
        // The device is an iPad
        return YES;
    }else{
        // The device is an iPhone or iPod touch
        return (interfaceOrientation == UIInterfaceOrientationPortrait | interfaceOrientation == UIInterfaceOrientationPortraitUpsideDown);
    }

}

// Disable autorotation for iPhone iOS6 and enable autorotation for iPad iOS6
// iOS6 support
-(BOOL)shouldAutorotate
{

    if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad){
        // The device is an iPad
        return YES;
    }else{
        // The device is an iPhone or iPod touch
        return NO;
    }

}

// Support portrait only orientation for iPhone iOS6 and all orientations for iPad iOS6
// iOS6 support
-(NSUInteger)supportedInterfaceOrientations
{

    if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad){
        // The device is an iPad
        return (UIInterfaceOrientationMaskAll);
    }else{
        // The device is an iPhone or iPod touch
        return (UIInterfaceOrientationMaskPortrait | UIInterfaceOrientationMaskPortraitUpsideDown);
    }

}

#pragma mark - View rotation methods

// iOS5 support

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation

{

// Support portrait only orientation for iPhone iOS5

if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad){

// The device is an iPad

return YES;

}else{

// The device is an iPhone or iPod touch

return (interfaceOrientation == UIInterfaceOrientationPortrait | interfaceOrientation == UIInterfaceOrientationPortraitUpsideDown);

}

// Disable autorotation for iPhone iOS6 and enable autorotation for iPad iOS6

// iOS6 support

-(BOOL)shouldAutorotate

{

if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad){

// The device is an iPad

return YES;

}else{

// The device is an iPhone or iPod touch

return NO;

}

// Support portrait only orientation for iPhone iOS6 and all orientations for iPad iOS6

// iOS6 support

-(NSUInteger)supportedInterfaceOrientations

{

if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad){

// The device is an iPad

return (UIInterfaceOrientationMaskAll);

}else{

// The device is an iPhone or iPod touch

return (UIInterfaceOrientationMaskPortrait | UIInterfaceOrientationMaskPortraitUpsideDown);

}

Segue – prepareForSegue

Make sure to give the segue an ID so that it can be found. In this example the segue ID would be “mySegueID”.

// prepareForSegue

-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
   NSLog(@"prepareForSegue: %@", segue.identifier);

   if ([segue.identifier isEqualToString:@"mySegueID"]) {

      // do something here...

   }
}

// prepareForSegue

-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender

{

NSLog(@"prepareForSegue: %@", segue.identifier);

if ([segue.identifier isEqualToString:@"mySegueID"]) {

// do something here...

}

XCode – Size and designation iOS icons (Icon Sizes and Names) for iPhone and iPad

Device / Screen	File Name (PNG)	Icon Size (pixels)
iPhone and iPod
Application Icon for iPhone (retina display)	Icon@2x.png	114 x 114
Application Icon icon for iPhone	Icon.png	57 x 57
Settings / Spotlight icon for iPhone (retina display)	Icon-Small@2x.png	58 x 58
Settings / Spotlight icon for iPhone	Icon-Small.png	29 x 29
Launch image Portrait (retina display)	Default@2x.png	640 x 960
Launch image Portrait	Default.png	320 x 480
iPhone 5
IPhone 5 Launch image for Portrait (retina display)	Default-568h@2x.png	640 x 1136
iPad
Application Icon for the new iPad (retina display)	Icon-72@2x.png	144 x 144
Application Icon for the iPad	Icon-72.png	72 x 72
Settings / Spotlight icon for iPad	Icon-Small-50@2x.png	100 x 100
Settings / Spotlight icon for iPad	Icon-Small-50.png	50 x 50
Launch image Portrait (retina display)	Default-Portrait@2x.png	1536 x 2008
Launch image Portrait	Default-Portrait.png	768 x 1004
Launch image Landscape (retina display)	Default-Landscape@2x.png	2048 x 1496
Launch image Landscape	Default-Landscape.png	1024 x 748
iTunes App Store
App icon for the App Store (retina display)	iTunesArtwork@2x.png	1024 x 1024
App icon for the App Store	iTunesArtwork.png	512 x 512

NSNotificationCenter – post and listen for a notification

In your first view controller (where you need to be notified of some event) you implement code to register and remove notification.

- (void)viewDidLoad
{
    [super viewDidLoad];
// add an observer to listen for the notification
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(doSomeAction) name:@"DisplayModalControllerNotification" object:nil];

}

// this action fires when we receive a notification
- (void)doSomeAction {

   // do something here when the notification is received
}

// be sure to remove the notification observer
- (void)dealloc {
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}

- (void)viewDidLoad

{

[super viewDidLoad];

// add an observer to listen for the notification

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(doSomeAction) name:@"DisplayModalControllerNotification" object:nil];

}

// this action fires when we receive a notification

- (void)doSomeAction {

// do something here when the notification is received

}

// be sure to remove the notification observer

- (void)dealloc {

[[NSNotificationCenter defaultCenter] removeObserver:self];

}

Now with the code above in place in your first view controller you will simply call it whenever you need it with this line of code which posts the notification:

// post a notification
[[NSNotificationCenter defaultCenter] postNotificationName:@"DisplayModalControllerNotification" object:nil];

1 2	// post a notification [[NSNotificationCenter defaultCenter] postNotificationName:@"DisplayModalControllerNotification" object:nil];

iOS Code Snippets

A collection of useful resources for iOS developers

Read and Write Array, Dictionary and Other Collections to Files

Read and Write Collections to File

Write/Read data to .plist file

How to change Status Bar text color in iOS 7

Change the Back button Title in iOS UINavigation

iOS7 – Stop views from going under the navigation bar or tab bar in your viewController

UIAlertView – a simple text input dialog box

View rotation methods

Segue – prepareForSegue

XCode – Size and designation iOS icons (Icon Sizes and Names) for iPhone and iPad

NSNotificationCenter – post and listen for a notification