Tag Archives: xcode


I know its been awhile since I’ve posted on here.  About a month ago, I got a new job where I’m working overnights so its been tough getting programming as a hobby in and especially writing as it while I adjust to the new work shift.  Some projects I’ve been working on:

1. I’ve gotten real heavy into using microprocessors.  Recently, I’ve gone to programming on the Arduino to using the ATMega in its own circuit (programmed while on the Arduino board for testing and then once ready to complete, finishing it on its own circuit.)

2. As usual, working on an XFDL for Linux project.  The GUI in WXWidgets is coming along, working out using libxml2 to parse the file, which is taking awhile but its beginning to flow.  Keep checking back for updates as they happen.

3. Finally got a Mac OSX running with xCode in Virtual Box.  I’m going to get back into Objective C and iPhone apps as I get it working more smoothly.

Thank you for checking in, I’ll be posting more regularly from here on out.

Navigating views on iPhone.

Its been awhile since I’ve posted anything, but I’ve been obsessing over an iPhone application.  I have three views set and was able to switch forward to next views pretty easily following several online tutorials that were available.  My favorite of which is this blog/tutorial.

That’s all well and good that I can move my views forward but how do I go back?  For this, I had to use some time, Google and Apple’s references and was able to find how to utilize the navigation controller.  See, my views did not have room for a navigation bar but I had used buttons to do the same.

After much testing and research, I found this simple line of code to move the page back.  In fact, once I used that everything about the navigation controller began to make sense!  I was just sad that there were no blog posts, tutorials or forums that had this method listed, so I decided to make sure there was at least one!

// Method: - (UIViewController *)popViewControllerAnimated:(BOOL)animated

-(IBAction)pageBack:(id)sender {
	[self.navigationController popViewControllerAnimated:YES];

Fern Screensaver : Part 4

I’ve now completed the Fern Screensaver in Objective-C for the Mac!  Surprisingly, using Objective-C was not that far from C/C++.  In fact, much of my code could be pasted directly in.  That includes the variables, math functions, etc.  Also, Mac has done a good job of documenting it’s libraries so using the NSObjects was not that difficult between Google and a quick reference search along with the example screensaver code.  I’m going to hit a few key differences and then post the entire file I edited.  XCode does the templating pretty well.

First, all the variables are at the top of the code so they don’t change as the program advances frames.

float mat[4][7] = {

@implementation ZackScreenSaverView

Secondly, I had to use implement my NSObjects at the start of the -(void)animateOneFrame method.  The size = [self bounds].size; calls the screensize.  It’ll take some time to get used to the method calls in Objective-C!

- (void)animateOneFrame
	NSRect dot;
	NSSize size;
	NSColor *color;
	NSBezierPath *path;
	float red,green,blue,alpha;

	size = [self bounds].size;

The framework has some good methods for getting random floats, or any integer type!

	// random number
	p = SSRandomFloatBetween(0.0,1.0);

Finally, it took some new methods to draw my dots to the screen.

	// set dot
	dot = NSMakeRect(jx,jy,1.0,1.0);

	// make dot
	path = [NSBezierPath bezierPathWithRect:dot];

	// draw dot
	[path stroke];

Other than that, the rest is pretty much the same.  I encourage those more used to Objective-C and programming for Mac products to comment about the use of this code and correct any bad assumptions!  Here is the code in it’s entirety (note that I’ve taken out the redraw at this time)…

//  ZackScreenSaverView.m
//  ZackScreenSaver
//  Created by Zachary D. Skelton on 5/30/10.
//  Copyright (c) 2010, Skelton Networks. All rights reserved.

#import "ZackScreenSaverView.h"

float mat[4][7] = {
// constant sets
float xa = -5.5;
float xb = 6.5;
float ya = -0.5;
float yb = 10.5;
// x and y to be altered
float x = 0.0;
float y = 0.0;
// screen/image size
int ix = 512;
int iy = 512;
// floats for math fulction
float p = 0.0;
float x0 = 0;
float jx = 0;
float jy = 0;
// variables to control function
int i = 0;
int k = 1;
int end = 10000;

@implementation ZackScreenSaverView

- (id)initWithFrame:(NSRect)frame isPreview:(BOOL)isPreview
    self = [super initWithFrame:frame isPreview:isPreview];
    if (self) {
        [self setAnimationTimeInterval:1/30.0];
    return self;

- (void)startAnimation
    [super startAnimation];

- (void)stopAnimation
    [super stopAnimation];

- (void)drawRect:(NSRect)rect
    [super drawRect:rect];

- (void)animateOneFrame
	NSRect dot;
	NSSize size;
	NSColor *color;
	NSBezierPath *path;
	float red,green,blue,alpha;

	size = [self bounds].size;

	ix = size.width;
	iy = size.height;
	dot = NSMakeRect(ix/2,iy/2,1.0,1.0);

	red = 255.0;
	green = 255.0;
	blue = 255.0;
	alpha = 255.0;
	color = [NSColor colorWithCalibratedRed: red
									  green: green
									   blue: blue
									  alpha: alpha];

	[color set];

	// random number
	p = SSRandomFloatBetween(0.0,1.0);

	// find random i
	if(p <= mat[0][6])
		i = 0;
	else if(p <= (mat[0][6] + mat[1][6]))
		i = 1;
	else if(p <= (mat[0][6] + mat[1][6] + mat[2][6]))
		i = 2;
		i = 3;

	// super math function
	x0 = ((x*mat[i][0])+(y*mat[i][1])+mat[i][4]);
	y = (x*mat[i][2]+y*mat[i][3]+mat[i][5]);
	x = x0;
	jx = ((x-xa)/(xb-xa)*(ix-1));
	jy = (iy-1)-(y-ya)/(yb-ya)*iy-1;

	// set dot
	dot = NSMakeRect(jx,jy,1.0,1.0);

	// make dot
	path = [NSBezierPath bezierPathWithRect:dot];

	// draw dot
	[path stroke];

	if(k == end) {
		k = 0;
	} else
		k += 1;

- (BOOL)hasConfigureSheet
    return NO;

- (NSWindow*)configureSheet
    return nil;


Fern Screensaver : Part 1

So my brother has asked me to help in making some iPhone/iPad applications.  Sounds like a great idea, I just need to get used to Objective-C.  If you already know C/C++, it’s not a huge leap to produce some iPhone code.  But I’m short of ideas to write and since most of the Mac is using Objective-C, I’ve decided practicing that language with something else, a screen saver!

I have done a simple screen saver using this excellent article to draw shapes.  I’ve decided to go from utilizing already produced code to doing something of my own.  My wife, who is a botanist at Iowa State was kind enough to loan me a Mac with Snow Leopard loaded, as school is out for the summer and they do not need this for their classes.  I asked her what she would like, and of course, it’s ferns (that’s the plant she studies).  Some quick thinking and googling lead me to the idea to use fractals!  In particular, Barnsley’s Fern.  To learn more, use google and this link.

Math drew this with a fractal equation, not by hand.

Now, as I have shown previously, I’m much better with Python, so to prototype the mathematical equation and code idea, I’ve developed a sample using pygame.  I found the math through this excellent code snippet, which saved me a lot of time in testing.  The use of the code is explained in the comments:

import random, pygame, time
from PIL import Image
from pygame.locals import *
from pygame.color import THECOLORS as color

mat = [[0.0,0.0,0.0,0.16,0.0,0.0,0.01],

xa = -5.5
xb = 6.5
ya = -0.5
yb = 10.5

x = 0.0
y = 0.0

imgx = 700
imgy = 700

k = 1
end = imgx*imgy / 10 * 4 # Looks like nothing is happening after this point.

screen = pygame.display.set_mode((imgx, imgy), 0, 8 )
pygame.display.set_caption('Fern Screensaver')

done = False
while not done:
    if k == end:
        k = 0
        p = random.random()
        if p <= mat[0][6]:
            i = 0
        elif p <= mat[0][6] + mat[1][6]:
            i = 1
        elif p <= mat[0][6] + mat[1][6] + mat[2][6]:
            i = 2
            i = 3
        x0 = x * mat[i][0] + y * mat[i][1] + mat[i][4]
        y = x * mat[i][2] + y * mat[i][3] + mat[i][5]
        x = x0
        jx = int((x-xa)/(xb-xa)*(imgx-1))
        jy = int(imgy-1)-int((y-ya)/(yb-ya)*imgy-1)
        c = color['white']
        screen.set_at((jx, jy), c)
    events = pygame.event.get()
    for e in events:
        if e.type == KEYDOWN and e.key == K_ESCAPE or e.type == QUIT:
            done = True
    k += 1


So, the next step is to code this for the Mac… keep posted for that code/tutorial.