Xcode cant find the method


Hello guys,

Its my first post here. I love this book!!
Quick introduction : Its my first book about Objective-C and I have nooo programming experience whatsoever.
I just want to make app’s, and I want to do it professionally. I am from Belgium and I teach it to myself 6 hours a day while im at work. ( im 20years old )

I understand most things, and other things come more clearer when I continued reading, so far so good but I still need to learn ALOT!

My problem is, as you will see in the images, and I still dont understand what I did wrong… Is that xcode cant find the methode in the main.m file, when it is clearly in my header file.

Can you guys see what I did wrong?
( link to image where you see that xcode says that he cant find the method)

(link to image where you can clearly see that it is in the header

Im looking forward for an solution.

Kind regards



I see that my WeightInKilos whas typed as WeightInMeters, I changed that now, but still it is given me the same error.

Just for letting you know,



I’m not 100% positive, but I think I found your problem…

Person *Dylan = [[Person alloc] init];
//This is where your code goes wrong
[Person setWeightInKilos: 99];

Since you used *Dylan your code should instead look like this:

[Dylan setWeightInKilos: 99];



That whas indeed the problem :stuck_out_tongue: i feel so stupid I didnt see that.
A big thank you for your answer.

Now I have a small extra question;

Why does my header and so start with PersonAppDelegate? It doesnt do sow in the book?
Or is this because I am working with Xcode5.

Kind regards,


Hi Dylan,

When you created your project, you must have used “Person” as the “Class Prefix” in the second window (Choose options for your new project:), where you add the “Product Name” etc.

You don’t have to add anything here, however most people will use their initials, or initials of their company etc.