The blog of Matthijs Hollemans, indie app maker and author of The iOS Apprentice

Comments

1. Richard Mansfield says:

   Sounds like an awesome book, I look forward to seeing the first chapter! Thanks!
2. Robert says:

   Keep up the good work.
3. Brandon says:

   ive been working through the first chapter and it’s amazingly awesome. It’s explained the basics very very well. I’ve read several other books and I’ve never quite grasped the info.

   I’m looking forward to the book, if the rest of it is as well done as this chapter my skills will jump leaps and bounds more.

   Thanks!
4. kyle says:

   Great so far. Just a minor typo I thought I’d bring to your attention. Under “Alternative ways to calculate the difference” you have:

   “If you took math in school,….

   int difference = abs(target – currentValue);”

   instead of:

   int difference = abs(targetValue – currentValue);
5. kyle says:

   Also is there a reason you don’t just call

   [self updateLabels];

   within the startNewRound method? Seems whenever you call it, it is following [self startNewRound]
6. Matthijs says:

   Thanks for the feedback, Kyle. I’ll fix the typo.

   You’re right that I could have called updateLabels from within startNewRound. The reason I didn’t is that I like to keep “model” code separate from “view” code. There’s more about the distinction between models and views in the second chapter, but the idea is that startNewRound just sets up the variables correctly and updateLabels just updates the screen. I find it cleaner to keep those concerns separated, but ultimately it doesn’t really matter and what you propose works just as well.
7. chori says:

   Heyy, how long till the rest of the book is released???
8. Matthijs says:

   @chori: Because the ebook talks a lot about iOS 5, it’ll have to wait until iOS 5 is released. But I’m glad you can’t wait.
9. Jonathan says:

   I have just finished chapter one and I love it. It was so clear and easy to follow where you were going. I liked the fact that after you have taught it the first time you push us to try it on our own for the subsequent times.

   I do have one question/issue. After I added background images to the slider, and then launch the app, both the left slider and right slider images display immediately, but the target image for the slider button does not display in my simulator until I click on it to drag it.

   Do you have any ideas as to what I should change or look into? Thanks for any advice/direction you can give.
10. Matthijs says:

    @Jonathan Thanks! I’m not sure why the slider button wouldn’t work right away. Maybe you can compare your version of the source with the code from the Source-Pretty folder and see if there are any differences. Also, what happens if you try to run that project?
11. Jonathan says:

    Thank you for your quick response. Great idea to see if the Source-Pretty version is working properly. I did a build and run on the Source-Pretty version and it worked perfectly. Then I started comparing source.

    Since it had to do with displaying the slider graphics and we did that all in code, I knew the the problem had to be in the area of the [self.slider] code in BullsEyeViewController.m in the viewDidLoad method.

    What I found was that I had left out the call to stretchableImageWithLeftCapWidth: topCapHeight.

    So I had:
    UIImage *trackLeftImage = [UIImage imageNamed:@"SliderTrackLeft"];

    I should have had:
    UIImage *trackLeftImage = [[UIImage imageNamed:@"SliderTrackLeft"] stretchableImageWithLeftCapWidth:14 topCapHeight:0];

    Completely my fault, you have it right in the source and in the tutorial. Thanks for reminding me that you gave the source.
12. chori says:

    Thanks for the reply, but iPhone V5 is aages away!
    I went through tutorial last week and it was amazing. But i’m already staring to forget it
    Any tips you can give to keep it fresh in my mind?
    Like any more tutorials? or just keep doing it again and again?
13. jed says:

    Thanks for the great tutorial. This is going to change my (coding) life!

    A couple things:
    1) The tutorial did not mention this, but were we supposed to declare the following in the .h file?
    - (void)startNewRound;
    - (void)updateLabels;
    - (void)startNewGame;

    Without these in the .h file, I get the following error:
    Automatic Reference Counting Issue: Receiver type ‘BullsEyeViewController’ for instance message does not declare a method with selector ‘startNewRound’

    2) I think this line:
    @interface BullsEyeViewController : UIViewController {

    should read:
    @interface BullsEyeViewController : UIViewController

    3) Please keep making these awesome tutorials! I’m a bit stuck with a “SIGBART” error but I can’t wait to get through the rest of the tutorial.
14. Matthijs says:

    Hi jed,

    Cool, I’m glad you like it.

    1) You could declare those methods in the .h file, but if you put them in the .m file where the tutorial told you to put them then there should be no compiler warnings. My guess is that you placed those methods *below* the point in the file where they are called.

    2) You’ll have to give me a little more context than that. Where in the tutorial does it say that?

    3) A SIGABRT error means that the system frameworks caught you doing something you weren’t supposed to. Often that means you forgot to hook something up in Interface Builder. You should see a message in the Debug pane that tells you what went wrong. If you don’t, then type “po $eax” after the (gdb) prompt when the app crashes (without the double quotes).

    Let me know how it goes!
15. Hoppo says:

    Hi Matthijs, Awesome tutorial. I’ve been playing with Xcode and objc for years but never got past the first hurdles. i.e. of actually understanding the processes. I always come back for more like a sucker for punishment. This time, after finding your tutorial it has opened up a new world for me, and I finally feel like I’m now standing on my own two feet. (Or coding with my own two hands!). Now I’m hungry for more. Can you tell me, does your book contain tutorial 2 and 3 that are for sale on the raywenderlich site? If so would I be best off just buying the book?
    Many Thanks.
16. Matthijs says:

    Hi Hoppo, it’s good to see my tutorial is helping you get a grip on Objective-C. I’m sorry if it wasn’t clear, but I decided to split up the book into separate parts. So it is no longer “the book” but “the series”. What you see at raywenderlich.com is what you get.
17. Mark says:

    Hey, is there still going to be five tutorials, or is it now just the three that are already complete and on raywenderlich.com?
18. Matthijs says:

    There will be one more tutorial and I’m working on it as we speak. So 4 parts total. My original planning was 5 parts but as it turned out I could fit all the material into 4 (longer) parts instead.
19. Mark says:

    Cool! If i purchase the series now will the 4th tutorial come included as a later download or will it be a standalone product purchased seperately?
20. Matthijs says:

    The current bundle does not include part 4 but the new bundle will, but it will also be more expensive. Anyone who has bought the 1-3 bundle can get part 4 for a few bucks less, so it is an upgrade but you don’t end up paying anything more than anyone buying the 1-4 bundle. The final price still has to be determined, though.
21. Ken says:

    I finished the first tutorial (great!) and am in the second. When I created the CheckListItem.h file Xcode didn’t include the initialization code that you show in the tutorial:

    – (id)init
    {
    self = [super init];
    if (self) {
    // Initialization code here.
    }

    return self;
    }

    The program seems to run fine without it. I also manually put it in, and the program still runs okay.

    Was there some change that now means it is no longer required? Should it be manually added if Xcode doesn’t put it in?
22. Matthijs says:

    Hi Ken,

    Apparently the Xcode templates have changed slightly since I wrote the tutorial. Previously Xcode would insert that init method for you but now it no longer does.

    If you decipher that method you’ll notice that it doesn’t actually do anything. It calls [super init] and then returns self. If you leave this whole method out, then the compiler automatically does the exact same thing. So it’s no big deal if this method is present or not because in that form it doesn’t actually do anything.
23. Ken says:

    Matthijs,

    Thanks — I was wondering if not calling [super init] mattered, but you have made it clear that it doesn’t in this circumstance. That’s one more thing I’ve learned from this process. Now to keep on learning…
24. Anmar says:

    Matthijs,
    I bought the series the tutorials are excellent and highly recommended, can you do a tutorial on how to edit a UItableView using the insertion controller rather than a separate add button?

    Thanks
25. Matthijs says:

    Thanks, Anmar. If you understand the basics of how a UITableView works, then the Apple documentation should be all you need. See here: http://bit.ly/wMhwQI
26. Deepak Lakkad says:

    Thanks for this awesome tutorial.