NSData General
Convert NSData To String
NSString *MyString = [[NSString alloc] initWithData:MyData encoding:NSUTF8StringEncoding];[MyString release];
Convert String To NSData
NSData *data = [myString dataUsingEncoding:NSUTF8StringEncoding];Length
if (data.length > 0)Accessing Individual Bytes
UInt8 *bytes = (UInt8 *)data.bytes;if (data.length >= 4)NSLog(@"Byte0: %d, Byte1: %d, Byte2: %d, Byte3: %d", bytes[0], bytes[1], bytes[2], bytes[3]);
Create NSData From File
NSData *data = [NSData dataWithContentsOfFile:filePath];Create NSData From String
NSData *TxData = [@"Hello World" dataUsingEncoding:NSUTF8StringEncoding];Create NSData From Byte Array
UInt8 TxDataBytes[10];int TxDataIndex = 0;TxDataBytes[TxDataIndex++] = 0x01;TxDataBytes[TxDataIndex++] = 0x02;TxDataBytes[TxDataIndex++] = 0x03;TxDataBytes[TxDataIndex++] = 0x04;NSData *TxData = [NSData dataWithBytes:&TxDataBytes length:TxDataIndex];
Copy Data To Array
NSMutableArray *ReceivedData = (NSMutableArray *)[data bytes];
Activity Indicator General
Drag onto window and place as requried
Select and turn on ‘Hide When Stopped’ from it’s properties.
Declare in #ViewController.h
IBOutlet UIActivityIndicatorView *activityIndicator;In #ViewController.m
//If view could be unloaded//********** VIEW DID UNLOAD **********- (void)viewDidUnload{[super viewDidUnload];[activityIndicator release];activityIndicator = nil;}//********** DEALLOC **********- (void)dealloc{[activityIndicator release];[super dealloc];}To turn on and off[activityIndicator startAnimating];[activityIndicator stopAnimating];
Message Box (Action Sheet) General
Show a main window message box
Alert View will automatically adjust for landscape orientationUIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"The username and password entered are not valid"message:nildelegate:nilcancelButtonTitle:@"OK"otherButtonTitles:nil];[alert autorelease];[alert show];
Show A Message Box
ActionSheet doesn’t auto adjust for landscape orientationUIActionSheet *actionSheet = [[UIActionSheet alloc] initWithTitle:@"A Message To Display"delegate:nilcancelButtonTitle:@"OK"destructiveButtonTitle:nilotherButtonTitles:nil];[actionSheet showInView:[[self view] window]];[actionSheet autorelease];
OK Cancel Message Box
In your method that want’s to show the action box
UIActionSheet *actionSheet = [[UIActionSheet alloc] initWithTitle:@"A Message To Display"delegate:selfcancelButtonTitle:@"Cancel"destructiveButtonTitle:@"OK"otherButtonTitles:nil];[actionSheet showInView:self.view];[actionSheet autorelease];
Add the delegate to the classes @interface
@interface #ViewController_iPhone : UIViewController<UIActionSheetDelegate>{
Add the delegate method
//*******************************************//*******************************************//********** ACTION SHEET DELEGATE **********//*******************************************//*******************************************- (void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex{// the user clicked one of the OK/Cancel buttonsif (buttonIndex == [actionSheet destructiveButtonIndex]){//----- CLICKED OK -----}else if (buttonIndex == [actionSheet cancelButtonIndex]){//----- CLICKED CANCEL -----}}
Multiple Buttons
UIActionSheet *actionSheet = [[UIActionSheet alloc] initWithTitle:@"A Message To Display"delegate:selfcancelButtonTitle:@"Cancel"destructiveButtonTitle:nilotherButtonTitles:@"Test1",@"Test2",nil];[actionSheet showInView:self.view];[actionSheet autorelease];
In
the actionSheet delegate the buttonIndex starts from 0 being the top
most button. If there is a destructiveButtonTitle then this is 0
otherwise it is the first otherButtonTitle.Downloading a file
Example of downloading a file and saving it in a directory in Documents
In the .h file
@interface AppMain : NSObject//-ADD THIS DELEGATE{FileDownloader *fileDownloader1; //-ADD THIS
In the .m file
//********** DOWNLOAD FILE **********- (void) SomeMethodName{NSLog(@"STARTING DOWNLOAD");if (!fileDownloader1)fileDownloader1 = [[FileDownloader alloc] init];[fileDownloader1 setDelegate:self];[fileDownloader1 DownloadFile:@"http://www.somedomain.com/somefile.html"];}//********** FILE DOWNLOAD FINISHED CALLBACK **********- (void)FileDownloadFinished:(NSData *)file{NSString *filePath;NSError *error;NSString *path;NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);path = [[paths objectAtIndex:0] stringByAppendingPathComponent:@"OurFiles"];//Create a new cache directoryif (![[NSFileManager defaultManager] createDirectoryAtPath:pathwithIntermediateDirectories:NOattributes:nilerror:&error]){NSLog(@"Create directory error: %@", error);}//Save the filefilePath = [path stringByAppendingPathComponent:@"somefile.html"];[[NSFileManager defaultManager] createFileAtPath:filePathcontents:fileattributes:nil];}
Edit
Free Disk Space
//*****************************************//*****************************************//********** GET FREE DISK SPACE **********//*****************************************//*****************************************-(float)GetFreeDiskSpaceInBytes{float totalSpace = 0.0f;NSError *error = nil;NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);NSDictionary *dictionary = [[NSFileManager defaultManager] attributesOfFileSystemForPath:[paths lastObject] error: &error];if (dictionary){NSNumber *fileSystemSizeInBytes = [dictionary objectForKey: NSFileSystemFreeSize]; //Or NSFileSystemSize for total sizetotalSpace = [fileSystemSizeInBytes floatValue];}else{NSLog(@"Error Obtaining File System Info: Domain = %@, Code = %@", [error domain], [error code]);}return totalSpace;}
Methods General
No Argument Methods
Declaring The Method
- (void)SomeMethodName;Coding The Method
- (void)SomeMethodName{}
Calling The Method
[self SomeMethodName];Single Argument Methods
Declaring The Method
- (int)SomeMethodName:(int)Value1;Coding The Method
- (int)SomeMethodName:(int)Value1{return 18;}
Calling The Method
[self SomeMethodName:34];Multiple Argument Methods
Declaring The Method
- (void)FileDownloaderCallback:(NSMutableData *)FileDatafileURL1:(NSString *)fileURL;
Coding The Method
- (void)FileDownloaderCallback:(NSMutableData *)FileDatafileURL1:(NSString *)fileURL
Calling The Method
[self FileDownloaderCallback:fileData fileURL1:DownloadingFileURL];
Memory General
Variable & Object Types
BOOL
Values:-
YES, NO
NSLog(@”The
answer is %i”, MyValue);
charUInt8
int
32bits
(currently unless the iPhone ever moves to a 64bit chipset). If
you want to future protect pointers for a 64bit system you can use
NSInteger instead.
NSLog(@”Value
= %i”, MyValue);
long
long / unsigned long longfloat
NSLog(@”Value
= %f”, MyValue);
double
NSLog(@”Value
= %f”, MyValue);
NSStringNSDate
NSObject
Most
classes in Objective-C are derived from NSObject:
idNSObject *object;object = [[NSObject alloc] init];NSLog(@"object = %@", object);[object release];
You
may be working with an object but you are not sure what that object
will be when the code executes. The id variable can be used as a sort
of placeholder for any object. It is often used in the Cocoa-Touch
frameworks and it is one of the things that contributes to the
powerful flexibility of the Objective-C programming language.
Currencyid someObject;someObject = object;NSLog(@"some object = %@", someObject);
A
good way is to use NSNumber and NSNumberFormatter together so that
the currency will always be localized for whatever country the device
is in.
NSNumber *MyValue = [NSNumber numberWithFloat:29.99];NSNumberFormatter *numberFormatter = [[NSNumberFormatter alloc] init];numberFormatter.numberStyle = kCFNumberFormatterCurrencyStyle;NSLog(@"The cost is %@", [numberFormatter stringFromNumber:MyValue]);[numberFormatter release];
static
Use static as for normal C to declare static variables: static NSString *SomeStringName;self (this)
self is the address of the object running the current method. It’s like ‘this’ in VC++. Typically it’s used so that an object can send a message to itself: [self SomeMethodName];super
super is used when you want to send a message to the self, but in it’s super class (instead of th method being looked for in the local class first): [super SomeMethodName];
Using NSMutableString
Mutable vs. Immutable Strings
NSMutableString – Should be used when you are physically changing the value of an existing string, without completely discarding the old value (i.e. adding a character to the beginning or end, modifying a character in the middle etc).NSString – Can never be changed after it has been created, only overwritten with a completly new string. Most NSStrings (including @”Constant Strings”) are autoreleased. NStrings occupy a fixed number of bytes in memory and are the most efficient.
NSLocalizedString – Return a localized version of a string
General
NSMutableString is a subclass of NSString. So any method which can take an NSString can also take an NSMutableString.Create A NSMutableString
Examples:NSMutableString *MyStringName;MyStringName = [[NSMutableString alloc] init];//Remember to release[MyStringName release];
Set NSMutableString Value
NSMutableString *MyStringName = [NSMutableString stringWithFormat:@"some text"];//or[MyStringName setString:@"new text"]; //Actually set the string value//BEWARE OF THIS!!MyStringName = SomeOtherNSMutableString;//This sets the pointer to another string object - don't use it!! This is a classic cause of bugs where you think you are writing text values but actually you are just updating the pointer, made worse by this not having requried "alloc] init]" to have been used causing unexplainable null value errors when you do decide to use setString!
Append To String
[MyStringName setString:@"abcd"];[MyStringName appendString:SomeOtherStringName];
Does NSMutableString Equal
//Test for is equalif ([MyStringName isEqualToString:@"SomeText"])//Test for NOT equalif (![OriginalMediaFileName isEqualToString:@""])
Convert Strings
myString = [myString lowercaseString];myString = [myString capitalizedString];
Add Variable to String
[TempString setString:[NSString stringWithFormat:@"%d days ago ", days]];
Retain
Using NSString
Mutable vs. Immutable Strings
NSMutableString – Should be used when you are physically changing the value of an existing string, without completely discarding the old value (i.e. adding a character to the beginning or end, modifying a character in the middle etc).NSString – Can never be changed after it has been created, only overwritten with a completly new string. Most NSStrings (including @”Constant Strings”) are autoreleased. NStrings occupy a fixed number of bytes in memory and are the most efficient.
NSLocalizedString – Return a localized version of a string
Guides
iOS DeveloperCreate A NSString
//Create a stringNSString *MyStringName1 = @"Hello";//Create new NSString from another stringNSString *MyStringName2 = [MyStringName1 stringByAppendingString:@", world!"];
Create NSString From Part Of NSString
NSString *source = @"0123456789";NSString *firstFour = [source substringToIndex:4];// firstFour is @"0123"NSString *allButFirstThree = [source substringFromIndex:3];// allButFirstThree is @"3456789"NSRange twoToSixRange = NSMakeRange(2, 4);NSString *twoToSix = [source substringWithRange:twoToSixRange];// twoToSix is @"2345"
Modifying a NSString
Use stringByAppendingString:This adds a string to an existing one and returns a new string. (Underneath NSString copies the old string to a new larger memory location, adds the argument and returns the new string.
NSString *MyString;MyString = [[MyArray objectAtIndex:0] stringByAppendingString:@"1234"];MyString = [MyString stringByAppendingString:@"5678"];
Add Variable to String
TempString = [NSString stringWithFormat:@"%d days ago ", days]];if ([MyStringName length] > 0)
Convert String To Variable
MyIntValue = [MyString intValue]; //Will equal 0 if string is not numericMyBoolValue = [MyString boolValue]; //Converts MyString to BOOL
NSString intialisation with NSMutableString
MyNSString = [NSString stringWithString:MyNSMutableString];//Doing this instead means you can now release or change MyNSMutableString without affecting MyNSString[MyNSMutableString release];
Does String Equal
if ([MyStringName isEqual:@"SomeText"])Does String Contain
if ([MyStringToCheck rangeOfString:@".mov" options:(NSCaseInsensitiveSearch)].location != NSNotFound){//Yes it does contain string}
Modify The End Of A String
NSRange EndRange = [MediaFileName rangeOfString:@".MOV"];if (EndRange.length > 0){MediaFileName = [MediaFileName substringToIndex:EndRange.location];MediaFileName = [MediaFileName stringByAppendingString:@".mov"];}
Get Characters Between Markers Within String
NSString *SourceString = @"[START]12345[END]";NSString *SubString;NSRange StartRange = [SourceString rangeOfString:@"[START]"];NSRange EndRange = [SourceString rangeOfString:@"[END]"];if ((StartRange.length > 0) && (EndRange.length > 0)){NSRange SubStringRange = NSMakeRange((StartRange.location + StartRange.length), (EndRange.location - (StartRange.location + StartRange.length)));SubString = [SourceString substringWithRange:SubStringRange];}else{SubString = @"";}
Convert Strings
NSString *MyNewString1 = [MyOtherString lowercaseString];NSString *MyNewString2 = [MyOtherString capitalizedString];
Get Character In String
if ([MyString characterAtIndex:1] == @"2")Remove Whitespace From String
MyString = [MyString stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];Convert NSString to ASCII value
NSString *MyString = @"A";int asciiCode = [MyString characterAtIndex:0]; //=65
Convert ASCII value to NSString
int asciiValue = 65;NSString *string = [NSString stringWithFormat:@"%c", asciiValue]; //="A"
Text Field General
Text fields are for single line text. For multi line text use Text View
Delegates
textFieldShouldReturn
Keyboard
return key pressed
Example Of Use
Declaring in #ViewController.h file
IBOutlet UITextField *MyTextFieldName;Releasing in #ViewController.m file
//********** VIEW DID UNLOAD **********- (void)viewDidUnload{[super viewDidUnload];[MyTextFieldName release];MyTextFieldName = nil;}//********** DEALLOC **********- (void)dealloc{[MyTextFieldName release];[super dealloc];}
Connecting in Interface Builder
Add the text filed to the viewRight click Files Owner
Drag the outlet to your text field
Storing Values Entered In A Text Field
[SomeIntVariable:[[SomeTextField text] intValue]];Dismissing The Keyboard & Responding To Input
Open the XIB.For each of the text fields, right click and drag the ‘delegate’ circle to ‘Files Owner’
Then in #ViewController.m:
//********** TEXT FIELD SHOULD RETURN **********- (BOOL)textFieldShouldReturn:(UITextField *)textField{[textField resignFirstResponder];return YES;}
If you have any methods in #ViewController.m that want to ensure the keyboard is removed:
//********** VIEW WILL DISAPPEAR **********- (void)viewWillDisappear:(BOOL)animated{[super viewWillDisappear:animated];[[self view] endEditing:YES]; //Ensure keyboard is removed}
TextView General
TextView is the same as TextField apart from TextView allowing multi-line editing. A TextView’s Return key enters the newline character whereas a TextField’s return key dispatches the delegate method ‘textFieldShouldReturn’.
Example Of Use
Declaring in #ViewController.h file
IBOutlet UITextView *MyTextViewName;Releasing in #ViewController.m file
//*************************************//*************************************//********** VIEW DID UNLOAD **********//*************************************//*************************************- (void)viewDidUnload{[super viewDidUnload];[MyTextViewName release];MyTextViewName = nil;}//*****************************//*****************************//********** DEALLOC **********//*****************************//*****************************- (void)dealloc{[MyTextViewName release];[super dealloc];}
Connecting in Interface Builder
Add the text filed to the viewRight click Files Owner
Drag the outlet to your text field
Storing Values Entered In A Text View
[SomeIntVariable:[[SomeViewField text] intValue]];Dismissing The Keyboard & Responding To Input
Open the XIB.For each of the text views, right click and drag the ‘delegate’ circle to ‘Files Owner’
Then in #ViewController.m:
//************************************************//************************************************//********** TEXT VIEW CHECK FOR RETURN **********//************************************************//************************************************- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text{if ([text isEqualToString:@"\n"]) //text is the new character being added{[textView resignFirstResponder];return FALSE; //False so the /n doesn't get added}return TRUE;}
If you have any methods in #ViewController.m that want to ensure the keyboard is removed:
//*****************************************//*****************************************//********** VIEW WILL DISAPPEAR **********//*****************************************//*****************************************- (void)viewWillDisappear:(BOOL)animated{[super viewWillDisappear:animated];[[self view] endEditing:YES]; //Ensure keyboard is removed}
Dismissing the keyboard when the user touches anywhere else (but not on another object)
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{UITouch *touch = [touches anyObject];if ([textView isFirstResponder] && [touch view] != textView){//The textView is currently being edited, and the user touched outside the text view[textView resignFirstResponder];}}
Detect Entering A Text View
//***************************************//***************************************//********** TEXT VIEW ENTERED **********//***************************************//***************************************- (BOOL)textViewShouldBeginEditing:(UITextView *)textView{if (textView == MyTextViewName){if (DoSometingVariable){MyTextViewName.text = @"";}}return YES;}
Set Text Colour
//Set to RGB valuemyText.textColor = [UIColor colorWithRed:153/255.0 green:204/255.0 blue:51/255.0 alpha:1];
Timer General
In the .h file:
NSTimer *showInfoBoxAfterDelayTimer1;In the .m file:
myTimer1 = [NSTimer scheduledTimerWithTimeInterval:1.5 //seconds (use decimal places if requried)target:selfselector:@selector(someMethodName)userInfo:nilrepeats:NO]; //NO = fire only once//[myTimer1 fire]; //< Use this to trigger it immediately- (void)someMethodName{
To Stop A Timer
//You can use this, but if you do it to a timer that has already been invalidated you crash[myTimer1 invalidate];//This avoids thatif ((myTimer1 != nil) && ([myTimer1 isValid])){[myTimer1 invalidate]; //Causes releasemyTimer1 = NULL;}
Don’t Use This To Stop A Timer Or To Check It’s Been Released
Don’t use it even after a timers only fire event! This can cause non descript crashing bugs that can be horrible to realize are actually beind caused the release of the timer!! Use the method above not this:if (myTimer1){[myTimer1 release];myTimer1 = nil;}
Web View General
Adding a simple WebView to a view
In #ViewController.h
IBOutlet UIWebView *webView1;In Interface Builder
Drag the Web View onto the viewConnect the webView outlet to it
Displaying an Internet URL
E.g. in #ViewController.m ViewDidLoad:NSString *urlAddress = @"http://www.google.com";NSURL *url = [NSURL URLWithString:urlAddress];NSURLRequest *requestObj = [NSURLRequest requestWithURL:url];[webView1 loadRequest:requestObj];
Setting The Zoom Level Of A Web View
[myWebView stringByEvaluatingJavaScriptFromString:@"document. body.style.zoom = 0.5;"];Scrolling A Web View
int scroll=20; //Pixels to scrollNSString* s=[[NSString alloc] initWithFormat:@"window.scrollTo(0, %i)",scroll];[webView stringByEvaluatingJavaScriptFromString:s];
Displaying Rich Text In A Web View
A useful way of displaying rich text labels etc.If you are using a webview as a label ensure you select it in the viewcontroller and turn off “user interaction enabled”, otherwise it will be dragable etc
NSString *MyHtml = @"<html><head><title></title><style type=\"text/css\">BODY {font-family:georgia; font-size: 14px;}</style></head><body>"; //Set default fontMyHtml = [MyHtml stringByAppendingString:@"<p>Some sample HTML text <strong>bold</strong>, <u>underlined</u>, <span style=\"color:#FF0000\">colored</span>.</p>"];MyHtml = [MyHtml stringByAppendingString:@"</body></html>"]; //The text to display[webView1 loadHTMLString:MyHtml baseURL:[NSURL URLWithString:@"http://www.google.com"]]; //The baseURL allows relative URLs within a document and can just use a dummy value
Note
that even doing this is in viewDidLoad (the earliest point for a
view) the web view typically won’t load until the view has
been shown the first time (i.e. slid into view) – very annoying.
You can’t force a webview to load before a view is shown, so
if you want to do it you have to do it programmatically: