Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

iOS Object-Oriented Objective-C Diving Deeper - Classes, Properties and Methods Custom Classes Continued

Ryan Jin
Ryan Jin
15,337 Points

How can if operation work with nonboolean

In this video, there is this piece of code.

-(id)init {
    self = [super init];

    NSLog(@"%@\n", self);

    if (self) {
        self.itemsOrdered = [[NSMutableArray alloc]init];

    return self;

I am wondering how can if statement be used to compare a self. Is it checking to see if self is nill or not, or is self a boolean type. I have printed it to the console, and it is not a boolean.

1 Answer

It's shorthand for a boolean: self != nil.

Here's a great article on the subject: https://www.mikeash.com/pyblog/the-how-and-why-of-cocoa-initializers.html