5: Buttons & Labels with Multiple Graphics in Objective-C

Creator Code 39 Extended in Objective-C 5: Buttons & Labels with Multiple Graphics

CHAPTER 5: Buttons & Labels with Multiple Graphics
Code 39 Encoder In Objective-C
Using Barcode drawer for iPhone Control to generate, create ANSI/AIM Code 39 image in iPhone applications.
www.OnBarcode.com
EAN13 Printer In Objective-C
Using Barcode creator for iPhone Control to generate, create EAN-13 image in iPhone applications.
www.OnBarcode.com
we want Apple to take care of mutability, but that we want to retain control of the memory. Later, we will synthesize these commands in the implementation file, for both IBOutlets. IBOutlets Remember them Oh yeah let s return to that part of your program. The IBOutlet for the text is UILabel with pointer *label, so enter the code for the text:
Barcode Maker In Objective-C
Using Barcode maker for iPhone Control to generate, create Barcode image in iPhone applications.
www.OnBarcode.com
Universal Product Code Version A Encoder In Objective-C
Using Barcode generation for iPhone Control to generate, create UCC - 12 image in iPhone applications.
www.OnBarcode.com
IBOutlet UILabel *label;
Painting GS1 128 In Objective-C
Using Barcode creator for iPhone Control to generate, create UCC.EAN - 128 image in iPhone applications.
www.OnBarcode.com
QR Code JIS X 0510 Printer In Objective-C
Using Barcode creator for iPhone Control to generate, create Denso QR Bar Code image in iPhone applications.
www.OnBarcode.com
The result will look like this:
ANSI/AIM Code 39 Encoder In Objective-C
Using Barcode encoder for iPhone Control to generate, create Code 3 of 9 image in iPhone applications.
www.OnBarcode.com
UCC - 12 Printer In Objective-C
Using Barcode creation for iPhone Control to generate, create GTIN - 12 image in iPhone applications.
www.OnBarcode.com
#import <UIKit/UIKit.h> @interface testViewController : UIViewController { IBOutlet UILabel *label; IBOutlet UIImageView *uiImageView; } @property (nonatomic, retain) IBOutlet UILabel *label; @property (nonatomic, retain) @end
Painting Code39 In VS .NET
Using Barcode creator for Reporting Service Control to generate, create Code39 image in Reporting Service applications.
www.OnBarcode.com
Read Code 3/9 In Java
Using Barcode reader for Java Control to read, scan read, scan image in Java applications.
www.OnBarcode.com
The IBOutlet for the picture is UIImageView with pointer *uiImageView, so enter the code for the picture:
GTIN - 12 Generation In Visual C#
Using Barcode drawer for .NET framework Control to generate, create UPC A image in Visual Studio .NET applications.
www.OnBarcode.com
Read QR Code In None
Using Barcode decoder for Software Control to read, scan read, scan image in Software applications.
www.OnBarcode.com
IBOutlet UIImageView *uiImageView; The result will look like this:#import <UIKit/UIKit.h> @interface testViewController : UIViewController { IBOutlet UILabel *label; IBOutlet UIImageView *uiImageView; } @property (nonatomic, retain) IBOutlet UILabel *label; @property (nonatomic, retain) IBOutlet UIImageView *uiImageView; @end
Create Barcode In Java
Using Barcode generator for Android Control to generate, create Barcode image in Android applications.
www.OnBarcode.com
Drawing PDF-417 2d Barcode In None
Using Barcode creator for Font Control to generate, create PDF417 image in Font applications.
www.OnBarcode.com
Are we done with the header file yet Not quite. We need to add our IBActions. We ve handled our IBOutlets, both of them, but now we re going to utilize an IBAction for something we really need here. Can you guess
Paint EAN / UCC - 14 In None
Using Barcode generator for Word Control to generate, create UCC.EAN - 128 image in Microsoft Word applications.
www.OnBarcode.com
Encode Barcode In None
Using Barcode generation for Software Control to generate, create Barcode image in Software applications.
www.OnBarcode.com
Adding IBActions
code 39 excel free
Using Barcode creator for Microsoft Excel Control to generate, create Code 3/9 image in Excel applications. barcode generator excel 2010 free code 39 excel free
www.OnBarcode.com
Encode Barcode In C#
Using Barcode creator for .NET Control to generate, create Barcode image in .NET applications.
www.OnBarcode.com
Yes, we need a button! So let s make an IBAction for a button. We could go deep again, into the code for the IBAction, but this has been a challenging section. Let s save the technical part of this element for Digging the Code.
Barcode Decoder In C#
Using Barcode Control SDK for VS .NET Control to generate, create, read, scan barcode image in .NET framework applications.
www.OnBarcode.com
Barcode Maker In .NET
Using Barcode encoder for ASP.NET Control to generate, create Barcode image in ASP.NET applications.
www.OnBarcode.com
CHAPTER 5: Buttons & Labels with Multiple Graphics
Meanwhile, just enter the new code that is highlighted here. See if you can anticipate the functions of the different pieces or parameters and we ll see how close you are later.
#import <UIKit/UIKit.h> @interface testViewController : UIViewController { IBOutlet UILabel *label; IBOutlet UIImageView *uiImageView; } @property (nonatomic, retain) IBOutlet UILabel *label; @property (nonatomic, retain) IBOutlet UIImageView *uiImageView; - (IBAction)buttonPressed:(id)sender; @end
Before exiting, copy ( C) the IBAction line:
- (IBAction)buttonPressed:(id)sender;
and save your work by entering good idea!
S. Of course, saving your work as you go is always a
Do you recall the reason for doing this We just copied the IBAction method (for our button) so you can paste it into the implementation file, to save time as we always like to do. OK, we re done with our header file! Go out now, and take a break.
Coding the Implementation File
Now that you re back from your much deserved break, let s continue. It s time to open up the helloWorld_005ViewController.m implementation file. 1. Use V to paste the line of code that you copied at the end of the previous section:
- (IBAction)buttonPressed:(id)sender;
The result should look like this:
#import "helloWorld_005ViewController.h" @implementation helloWorld_005ViewController - (IBAction)buttonPressed:(id)sender;
In the header file, we told the computer that we are going to do some action(s) when a button is pressed. Now that we ve pasted this set of commands into the implementation file, we replace the ; with a set of brackets. It is inside these brackets that we will tell the computer what needs to be implemented when the button is pressed.
CHAPTER 5: Buttons & Labels with Multiple Graphics
#import "helloWorld_005ViewController.h" @implementation helloWorld_005ViewController - (IBAction)buttonPressed:(id) sender{ }
Before we get into the code that will spring into action each time the user presses the button, we need to take care of the second half of the synthesis we began in the previous section. Do you remember how we defined our @property directive with a statement in the header file, and how we left the corresponding @synthesize directive for our implementation file Specifically, we had to have one @property directive for the UILabel and another for the UIImageView, as follows:
@property (nonatomic, retain) IBOutlet UILabel *label; @property (nonatomic, retain) IBOutlet UIImageView *uiImageView;
What this means is that we merely need to have an @synthesize statement for both the pointers, one for the UILabel and another for the UIImageView. We named the pointer for the UILabel named label, and we named the pointer for the UIImageView named uiImageView. We can put them both on the same line, so let s do it:
#import "helloWorld_005ViewController.h" @implementation helloWorld_005ViewController @synthesize label, uiImageView; (IBAction)buttonPressed:(id) sender{ }
We ve used a simple overlay of photograph and text to get you partially familiarized with a terribly difficult concept. Hey if your head is spinning, don t feel bad! Wrapping your brain around pointers, objects, and synthesis is not trivial. Unfortunately, there is no way around it in an iPhone/iPad app programming lesson. In the class in which I taught this exact assignment, there were a couple of computer science students with backgrounds in C++, C#, and Java who had a more difficult time than some of the liberal arts students in the class who just faithfully accepted that: The @property directive declares that our object has a property with a specific type. The @synthesize directive implements the methods we declared in the @property directive. The advanced students had so much stuff in their heads that it took some of them longer than the newbies to accept these two statements. We ll be going over these points again and again, so let s move on for now. These ideas can ferment in the back of your brains, and tomorrow these will make more sense.
Copyright © OnBarcode.com . All rights reserved.