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POCocoa: Accepting and responding to keystrokes
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  1. POCocoa: Accepting and responding to keystrokes
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    copied!<p>Hey everyone, I'm a newbie and I have what I anticipate will be a pretty easy question to answer. In order to learn a bit about event handling and drawing, I'm attempting to write a program that draws a black rectangle that increases in length every time the user hits the 'c' key. So far it just draws a black rectangle on a blue background without responding to keystrokes. Here is what I have so far:</p> <p>Input.h</p> <pre><code>#import &lt;Cocoa/Cocoa.h&gt; @interface Input : NSView { int length; } - (void)keyDown:(NSEvent *)theEvent; @end </code></pre> <p>Input.m</p> <pre><code>#import "Input.h" @implementation Input - (id)initWithFrame:(NSRect)frame { self = [super initWithFrame:frame]; length = 10; if (self) { // Initialization code here. } return self; } - (void)drawRect:(NSRect)dirtyRect { //set variables NSRect r1; NSBezierPath *bp; // set background color [[NSColor blueColor] set]; NSRectFill(dirtyRect); //set color to black &amp; draw r1 [[NSColor blackColor] set]; r1 = NSMakeRect(1, 1, length, 10); bp = [NSBezierPath bezierPathWithRect:r1]; [bp fill]; } - (void)keyDown:(NSEvent *)theEvent { NSString *key = [theEvent characters]; if ( [key isEqualToString:@"c"] ) { length += 10; } } @end </code></pre> <p>I copied the keyDown method from Cocoa in a Nutshell, by the way. Needless to say, I don't really understand it. Do I have to make connections in IB in order to get the program to recognize keystrokes? Basically, I would love it if somebody could help me to get this program to work, because as of yet I have not gotten anything to respond to keystrokes.</p> <p>And here's <a href="http://proquest.safaribooksonline.com/0-596-00462-1/cocoaian-CHP-3-SECT-9" rel="nofollow noreferrer">Cocoa in a Nutshell</a></p>
 

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