Koen Van Nieuwenhove (@CocoaCrumbs) will show us the basics of DTrace, the tool that’s behind Apple’s Instruments app.

The goal of the talk is to show what DTrace can do and thereby provide a better understanding of how Instruments works and how to interpret its output. The presentation will be at an introduction-level, consisting mostly of (live) examples to keep it as accessible as possible.

Practical information:

• Date: 26 April, 8pm
• Location: Het Trappenhuis (School), Lucas Munichstraat 29, 9000 Gent
• Topic: Koen Van Nieuwenhove will show us the basics of DTrace.
• Registration: http://www.eventbrite.com/event/3385701725

See you there

Update: Slides of the presentation can be downloaded here. Be sure to read the readme-file for the ‘tooManySecrets’ demo. Enjoy!

Our next Cocoaheads Belgium meeting will take place on the 26 th of March at 8 pm in the offices of 10to1 (Prins Boudewijnlaan 5, Kontich).

This time Johan Ronsse (designer at wolfslittlestore.be) will give a presentation on designing for iOS. He will use the upcoming ConcertWall app as a case study and will share his experience on the interaction between developer and designer. There will also be lots of design-related tips & tricks, useful for both designers and developers.

Practical information:

• Date: 26 March, 8pm
• Location: 10to1, Prins Boudewijnlaan 5, Kontich
• Topic: iOS design case study: from concept to end result. Presented by Johan Ronsse.
• Registration: http://www.eventbrite.com/event/3144050941

See you there

Update: Slides of the presentation are available at slideshare.net/Wolfr

Our next (informal) CocoaHeads meeting will be on 27 February, 8pm at Vooruit Gent.

The perfect time to talk about Objective-C, our secret projects, and of course with a couple beers.

This month the meeting will take place in Mons on the 27th of June.  Raphael and Sandrine from Creaceed have been kind enough to provide us with a location in which we can hold this month’s meeting.

The location for this month’s meeting is La Maison de l’Entreprise (LME) - Incubateur technologique, 7 Boulevard Initialis, 7000 Mons.  Raphael will be presenting a session on “GCD & Blocks”, an Steven from Blue CrowBar Software will open the meeting with a very special Steve(n)Note.

The meeting will start at 20:00, and there will be plenty of time to meet up with other Cocoa Heads BE enthousiasts. So if you’re interested, feel free to go to the EventBrite website and sign up, since spaces are limited.

You can find more information on CocoaHeads Belgium a the CocoaHeads Belgium website, in the CocoaHeads Google Groups and I even created a Linked In group for CocoaHeads Belgium.

Registration for this Meeting can be done on the Eventbrite page.  If you have suggestions for future sessions or are willing to give a session, that would be the perfect time to let us know.

This month the meeting will take place in Gent on the 2nd of May.  The location for this month’s meeting is in the offices of SHPArtners – Roving Bird, Kortrijksesteenweg 1099a, 9051 Gent.

The meeting will start at 20:00, and there will be plenty of time to meet up with other Cocoa Heads BE enthousiasts. So if you’re interested, feel free to go to the EventBrite website and sign up, since spaces are limited.

You can find more information on CocoaHeads Belgium a the CocoaHeads Belgium website, in the CocoaHeads Google Groups and I even created a Linked In group for CocoaHeads Belgium.

Registration for this Meeting can be done on the Eventbrite page. If you have suggestions for future sessions or are willing to give a session, that would be the perfect time to let us know.

You might be wondering what is meant by an All-Inclusive training. Well the price includes food and lodging during the 3 days course at the Domein Marinus in Zoersel.

If that’s not enough to convince you, we have been able to extend the early bird reduction for Cocoaheads Belgium members up till Jan 19 2011.

This means any Cocoaheads Belgium member, who registers prior to the 19th of January, will only pay 1.500 Euro (Excl. Taxes).

Course will be held in English

Course Program

• introducing Objective C
• memory management
• understanding MVC
• using views and layers & using scrollviews
• view controllers, tab controllers, navigation controllers, splitview controllers, popover controllers
• using camera and imagepickers
• tableviews / custom cells
• local persistence using sqlite
• accessing data on the internet and parsing xml
• using the built-in gps and accelerometer
• using gestures/shakes
• animating objects
• making your app multi-lingual and compatible with iPhone 4’s Retina display

Prerequisites

• General knowledge of an “OO” programming langauge (C++ / C# / Java of PHP)

Recommended

• a Mac with a recent version of Mac OS 10.6 en de most recent Xcode 3.x
• iOS Developer Account
• iDevice (iPhone, iPod Touch of iPad) + Cable

Trainers

Steven Vandeweghe

Steven is a seasoned Mac OS X developer with a great interest in 2D graphics. Steven has years of experience developing for Mac OS X and for iOS. Steven is the owner of Blue Crowbar Software.

Spencer Pieters

Spencer works for RovingBird and has a passion for anything related to mobile development. He is specialized in iOS and also has quite some experience developing for Andriod and Windows Phone 7.

Registration

You can register at Rovingbird.com

A NSCoderNight is basically an event where developers come together, shows some cool stuff, request support for technical issues and talk about the newest Objective-C and Cocoa stuff…

The first NSCoderNight will be in Ghent (in the neighborhood of 
Ghent Dampoort station) and will be at Thursday February the 24th 2011 
and start around 20:30.

I can get a location with a bar, WiFi-internet, some places to sit and power! What else do we need, except developers?

Are you interested and do you want to join the first NSCoderNight of CocoaHeadsBE? If so, please register at here, so we can arrange enough seats and tables.

More information about NSCoderNights at NSCoderNights-Website

This is a repost of my original article which I posted on my own website. But since it is related to iOS development, I thought it might be interesting for the Cocoaheads Belgium folks as well.

Colors Everywhere

Well, after my previous post I continued doing some more work on my UI and trying to create my own Style for UITableViews and UITableViewCells. I ended up using the same colors over and over again in all different places in my application. In the end I had code in my UITTableViewController which set the Color for the Background and the navigation bar :

- (void)viewDidLoad
{
    [super viewDidLoad];

    // Uncomment the following line to display an Edit button in the navigation bar
    // for this view controller.
    // self.navigationItem.rightBarButtonItem = self.editButtonItem;
    [[self navigationController] navigationBar].tintColor = [UIColor brownColor];
    UIImage *img = [UIImage imageNamed:@"BG_Pink"];
    [[self tableView] setBackgroundColor:[UIColor colorWithPatternImage:img]];
}

This was all working out quite nicely …

Using the same color scheme in other Views

Data Entry View with ColorScheme

Of course, my application consits of a few different UITableViews and I even added a data entry View and a detail view. As you can see, the data entry view is using the same background color for the UITableView and the UITableViewCells are using the same color as my other UITableView as well.

At some point, I wanted to change the color scheme I was using (it was more pinkish at the start), and use something more Orange or brown like. Sadly this required me to change the color in every spot where I was using it. When I tested it on my phone, it looked horrible, since I forgot to change a few colors.

Since I’m still developing some basic ideas for the app, and the color scheme might change a few times during the Development cycle, I started thinking. There surely must be an easier way to handle this, which wouldn’t require me to change the colors in 10 different places.

Of course, I could subclass UIColor and add my own colors to it, but I wanted to try a different approach

The Categories Approach

During the iOS bootcamp I took at Big Nerd Ranch Europe a while back, we touched on the subject of Categories. Categories allow you to extend a class without the need to Subclass it. Using Categories I could quickly add a few methods to UIColor whithout the need to create a new Subclass.

Creating a Category in UIColor

Creating a new category is actually quite easy. In my case, I wanted a category on UIColor so I could extend it. I created a new Header and Implementation file and called it UIColor+MyApp.h and UIColor+MyApp.c

The Header File

In the Header file UIColor+MyApp.h I added the following code :

//
//  UIColor+MyApp.h
//
//  Created by Stefaan Lesage on 11/11/10.
//  Copyright 2010 Devia. All rights reserved.
//

#import 

@interface UIColor (MyApp) 

+ (UIColor *)myTableViewBackgroundColor;
+ (UIColor *)myTableCellBackgroundColor;

@end

This simply declares a category MyApp on UIColor, and defines 2 new methods on it. myTableViewBackgroundColor which will return the Default color which should be used as the background for my UITableViews, and myTableCellBackgroundColor which defines the default color which should be used as the background for my UITableViewCells (and in some other places in my app).

The Implementation

In the Implementation file UIColor+MyApp.m I added the following code :

//
//  UIColor+MyApp.m
//  Phocation
//
//  Created by Stefaan Lesage on 11/11/10.
//  Copyright 2010 Devia. All rights reserved.
//

#import "UIColor+MyApp.h"

@implementation UIColor (MyApp)

+ (UIColor *)myTableViewBackgroundColor
{
    UIImage *img = [UIImage imageNamed:@"BG_Pink"];
    return [UIColor colorWithPatternImage:img];
}

+ (UIColor *)myTableCellBackgroundColor
{
    return [UIColor colorWithRed:255/255.0 green:240/255.0 blue:255/255.0 alpha:100];
}

@end

Well the implementation is pretty straightforward. For the myTableViewBackgroundColor, I simply return a UIColor based on the pattern in my previous post. The myTableCellBackgroundColor then returns the light pink / purple color which gets used as the background for my UITableViewCells.

Using the Category

Using the Category is now pretty Straight Forward. In my Detail View for example, I have a reference to a UITextField called nameTextField and to the tableView beneath it. So in my viewDidLoad I have the following code :

- (void)viewDidLoad
{
    [super viewDidLoad];

    /* Load our HeaderView if Necessary */
    [[self view] setBackgroundColor:[UIColor myTableViewBackgroundColor]];
    [[self tableView] setBackgroundColor:[UIColor myTableViewBackgroundColor]];
    [nameTextField setBackgroundColor:[UIColor myTableCellBackgroundColor]];
}

Quite simple, isn’t it ?

But what are the advantages ?

For me, it makes my code a little more readable (that is of course a more personal opinion), but what’s even better is that my code is a lot easier to maintain. If for some reason I want to change my color scheme to use another pattern or another color for the UITableViewCells, I only need to update the code in one sport. Simply modify the Implementation found in UIColor+MyApp.c, build and it’s done !

Once I found the advantages of this approach, I even added more methods to my UIColor+MyApp category. It now also contains methods which return the color I will be using for the UINavigationBar tine, colors I will be using for different texts in my application, …

Feedback

As with my previous post, there might be better ways to achieve the same thing. If you have a more appropriate approach or solution, feel free to let me know … I’m eager to learn

This is a repost of my original article which I posted on my own website. But since it is related to iOS development, I thought it might be interesting for the Cocoaheads Belgium folks as well.

The default grouped UITableView

The default Grouped UITableView looks nice but …

Well, you can use the UITableView in it’s Plain mode, but also in a Grouped mode. The Grouped mode uses some kind of pattern as the background for the UITableView. It looks quite nice and is made up of alternating light and darker blue-grayish lines.

I wanted someting a little more ‘Special’ …

Although the default look isn’t all that bad … I wanted to have something ‘special’ for my application. So I was wondering if there was some way to change the color used in that pattern. Since I didn’t know the answer myself, I sent out a tweet. I was hoping someone would pick it up and maybe let me know where I could find some more information on this topic.

The feedback I got

I did receive some feedback to my tweet: ‘Is there an easy way to create your own UIColor which looks like the ‘Group Table View Color’ but with another color scheme ? #iphonedev. One of the answers was from Amar Kulo who suggested to supply me with some Photoshop files I could modify.

A few moments later, Amar Kulo even provided me with a complete answer and wrote a blog post about it to help me out. It is actually pretty easy, so I thought i would share it with the world as well.

The Trick

It is actually quite easy to get your own custom background. You simply have to use a custom background image. Amar provides a few samples in his blogpost. The only thing you need to do is open up your favorite Image Editor (in my case Pixelmator), change the colors to you liking and create the necessary versions for your application.

The Code

Once you added the resources to your project, you can simply start using them as the background for your Grouped UITableView. In my case, it was simple a matter of setting the background color in the ViewDidLoad of my UITableViewController :

- (void)viewDidLoad
{
    [super viewDidLoad];

    // Uncomment the following line to display an Edit button in the navigation
    // bar for this view controller.
    // self.navigationItem.rightBarButtonItem = self.editButtonItem;
	UIImage *img = [UIImage imageNamed:@"BG_Pink"];
	[[self tableView] setBackgroundColor:[UIColor colorWithPatternImage:img]];
}

Feedback

I ended up with this Bakcground and Color Scheme

Well … This might not be the best way to do it, so if you have any suggestions, feel free to let me know.

Personally, I had to experiment a bit with quite a few different colors before I got something which did looked OK to me, so feel free to experiment as well, and let me know what you come up with

Next time I’ll be delving a little deeper into some more things I did with my UITableView and UITableViewCell … but for now … feel free to post a comment and have a look at the result :

Well, last month Eric Bariaux gave a presentation on Automated Testing in an iOS World during our Cocoaheads Belgium Meeting. I did video tape the session, but didn’t really find the time to process it yet … until then end of last week.

So I finally Imported the HDV Tapes, did some color correction, added a few titles, exported the whole thing … and ended up with a 90 GB file. I had to compress this into a smaller format for uploading and ended up with an 700 something Mb file which I uploaded to Vimeo.

Automated testing in an iOS World – Cocoaheads Belgium from Stefaan Lesage on Vimeo.

Audio Quality

I know the audio quality isn’t superb … We did have a lot of noise from the activity in the room next to ours, and I couldn’t really filter that out without messing up the rest of the audio. Next time I’ll try to bring an Audio Interface and a Microphone so we can record the audio separately.

High Quality Version

The file I uploaded had a resolution of about 640 x 360 pixels, which is perfect for displaying on an older iPhone / iPod Touch, but somehow low quality for viewing on the iPad. If people are interested in a higher quality version, I could generate an iPad specific version for you, but I won’t be able to upload that to Vimeo due to the file size.

Next Meeting

Well, since we should have had this months meeting yesterday … we will be skipping it and try to organize the next one on the 20 th December (if that’s find with everyone). We are still looking for a location or a topic, but we could also make it a ‘coding’ session if we can’t find someone to give a presentation.

Final Note

If anyone thinks he can help us out with one of the ideas mentioned in this topic, please do contact us. If you still have more ideas … well contact us as well., or even better … start organizing

Regards,

Stefaan