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vb.net print barcode labels Class NSFileHandle in Objective-C
Table 8.4 Make Denso QR Bar Code In Objective-C Using Barcode maker for iPhone Control to generate, create QR Code image in iPhone applications. www.OnBarcode.comBarcode Generation In Objective-C Using Barcode generator for iPhone Control to generate, create Barcode image in iPhone applications. www.OnBarcode.comWays to manipulate files using the SDK Method fileHandleForReadingAtPath: fileHandleForWritingAtPath: fileHandleForUpdatingAtPath: readDataOfLength: Summary Class methods that allow you to open a file UCC.EAN - 128 Maker In Objective-C Using Barcode creation for iPhone Control to generate, create GTIN - 128 image in iPhone applications. www.OnBarcode.comBarcode Encoder In Objective-C Using Barcode generator for iPhone Control to generate, create Barcode image in iPhone applications. www.OnBarcode.comClass NSFileHandle
Encoding EAN-13 In Objective-C Using Barcode encoder for iPhone Control to generate, create EAN-13 Supplement 5 image in iPhone applications. www.OnBarcode.comPaint QR-Code In Objective-C Using Barcode creation for iPhone Control to generate, create QR image in iPhone applications. www.OnBarcode.comNSFileHandle
Draw Barcode In Objective-C Using Barcode generator for iPhone Control to generate, create Barcode image in iPhone applications. www.OnBarcode.comMake GS1 - 12 In Objective-C Using Barcode creator for iPhone Control to generate, create GS1 - 12 image in iPhone applications. www.OnBarcode.comReturns an NSData containing the specified number of bytes from the file Returns an NSData with the rest of the file s content Closes an NSHandle Returns an NSData with the complete file s contents Creates an NSData with the complete file s contents Writes the NSData to a file Print Denso QR Bar Code In Java Using Barcode printer for Java Control to generate, create QR Code image in Java applications. www.OnBarcode.comGenerate QR Code JIS X 0510 In Objective-C Using Barcode printer for iPad Control to generate, create QR Code 2d barcode image in iPad applications. www.OnBarcode.comNSFileHandle
Code 3 Of 9 Creator In Visual Basic .NET Using Barcode encoder for VS .NET Control to generate, create Code 3/9 image in .NET framework applications. www.OnBarcode.comPDF-417 2d Barcode Creator In None Using Barcode creator for Excel Control to generate, create PDF-417 2d barcode image in Office Excel applications. www.OnBarcode.comreadDataToEndOfFile
Painting Barcode In Visual Studio .NET Using Barcode printer for .NET Control to generate, create Barcode image in .NET applications. www.OnBarcode.comGenerate 1D Barcode In VB.NET Using Barcode creator for .NET Control to generate, create Linear Barcode image in .NET framework applications. www.OnBarcode.comNSFileHandle NSFileManager
EAN128 Maker In Visual C# Using Barcode maker for .NET Control to generate, create GTIN - 128 image in .NET framework applications. www.OnBarcode.comUPC Code Creation In .NET Framework Using Barcode maker for ASP.NET Control to generate, create UPC Code image in ASP.NET applications. www.OnBarcode.comcloseFile contentsAtPath: Draw Barcode In VB.NET Using Barcode drawer for .NET framework Control to generate, create Barcode image in .NET framework applications. www.OnBarcode.comEAN-13 Supplement 5 Drawer In None Using Barcode encoder for Font Control to generate, create EAN13 image in Font applications. www.OnBarcode.comNSData
Drawing UCC - 12 In VS .NET Using Barcode printer for Reporting Service Control to generate, create UCC-128 image in Reporting Service applications. www.OnBarcode.comBarcode Recognizer In VS .NET Using Barcode decoder for .NET Control to read, scan read, scan image in .NET applications. www.OnBarcode.cominitWithContentsOfFile: NSData
writeToFile:atomically: Download from Wow! eBook <www.wowebook.com>
Opening files
Table 8.4 Ways to manipulate files using the SDK (continued) Method stringWithContentsOfFile:encoding:error: Summary Class method that returns an NSString with the complete file s contents Class NSString
NSString
initWithData:encoding: Returns an NSString with the NSData s contents Writes the NSString to a file
NSString
writeToFile:atomically:encoding:error: As table 8.4 shows, you can access files in a huge variety of ways after you ve created a file path. If you re a C programmer, opening a file handle, reading from that file handle, and finally closing that file handle is apt to be the most familiar approach. Or, you can use a shortcut and go straight to the NSFileManager and have it do the whole process. Even quicker is using methods from NSData or NSString to directly create an object of the appropriate type. Any of these simpler methods will cost you the ability to step through a file byte by byte, which may be a limitation or a benefit, depending on your program. But with the simpler methods, you need only a single line of code: NSString *myContents = [NSString stringWithContentsOfFile:myFile encoding:NSASCIIStringEncoding error:&error]; Table 8.4 also lists a few ways to write back to files, including simple ways to dump an NSData object or an NSString object to a file. There are also other ways. When you decide which set of methods you re most comfortable using, you should consult the approFile content priate class reference for additional details. In this section and in our next When you re working with files, you re example we re largely assuming that files contain plain, likely to be doing one of two things. Either unstructured text. But this you have files that contain large blobs of user doesn t have to be the case. information, or you have files that contain XML is a great way to store local short snippets of data that you ve saved for data in a more structured format. your program. To demonstrate how to use a 14 covers how to read XML and includes an example of few of the file objects and methods, you ll reading local XML data. tackle the first problem by building a simple notepad prototype. Filesaver: a UITextView example
This program lets you maintain a text view full of information from one session to another. It s relatively basic, but you can imagine how you could expand it to mimic the Notepad program, with its multiple notes, toolbars, navigator, and image background. Download from Wow! eBook <www.wowebook.com>
Data: actions, preferences, and files
Listing 8.4 shows this simple filesaver example. The objects, as usual, were created in Interface Builder: a UIToolBar (with associated UIBarButtonItem) and a UITextView. Listing 8.4 A prototype notepad program that maintains a text field as a file
@implementation filesaverViewController - (void)viewDidLoad { NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectory = [paths objectAtIndex:0]; Creates file path filePath = [documentsDirectory stringByAppendingPathComponent: @"textviewcontent"]; [filePath retain]; NSFileManager *myFM = [NSFileManager defaultManager]; if ([myFM isReadableFileAtPath:filePath]) { myText.text = [NSString stringWithContentsOfFile:filePath encoding:NSASCIIStringEncoding error:nil]; } keyboardIsActive = NO; [super viewDidLoad]; } Executes Done action -(IBAction)finishEditing:(id)sender { if (keyboardIsActive == YES) { [myText resignFirstResponder]; } - (void)textViewDidBeginEditing: (UITextView *)textView { if ([myText.text compare:@"Type Text Here."] == NSOrderedSame) { myText.text = [NSString string]; } keyboardIsActive = YES; } - (void)textViewDidEndEditing:(UITextView *)textView { [textView.text writeToFile:filePath atomically:YES encoding:NSASCIIStringEncoding error:NULL]; keyboardIsActive = NO; } ... @end This program shows how easy it is to access files. The hardest part is determining the path for the file, but that involves using the path-creation methods we looked at a few sections back. When you have your path, you save it as a variable so that you won t have to re-create the path later B. Next, you use NSFileManager to determine whether a file exists. If it does, you can immediately fill your UITextField with its content. Finally, you set a keyboardIsActive variable, which you update throughout the program.
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