Question

On the CS193p course they says that in an init method there should be an if statement to check if the [super init] works:

if (self = [super init]) {
    self.someProperty = parameter;    
}
return self;

I don’t understand why this is done, as if the [super init] returns nil, the method itself will also return nil, no matter the outcome of the if statement?

EDIT: The question is; why put self = [super init] inside an if statement. (Not: Why have self = [super init] at all)

Answer 1

That’s make sense because in some cases [super init] can return nil, and in this case if you try to access some ivar you’ll get crash.

Example:

-(id) init {
    self = [super init];
    some_ivar = [[NSObject alloc] init]; //compiler treats this as self->some_ivar
    //if self == nil you'll get EXC_BAD_ACCESS

    return self;
}