custom class = custom +alloc , custom +init

Question

I'm new with objective c for the iphone.

I'm writing a custom class, then, should I write my own +alloc, +init methods? I believe that: the +alloc will just call [thing alloc]; and the +init will perform something like: [thing setValue:X];

is there a "default" +alloc and +init methods? if yes, what should I wait for the default +alloc and +init?, let's say i have a NSMutableDictionary* i.e.

@interface class1 : NSObject {

    NSString *test; 
    NSMutableDictionary *map;
}

thanks

David Gelhar · Accepted Answer · 2010-07-27 17:53:19Z

5

You generally don't need to write your own +alloc method.

For your example, you might have an -init that looks like:

- (id)init {
    self = [super init];
    if (self) {
        map = [[NSMutableDictionary dictionary] retain];
    }
    return self;
}

Note that you first call the superclass -init, and check that it worked, before initializing your own variables.

answered Jul 27, 2010 at 17:53

David Gelhar

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Jacob Relkin · Accepted Answer · 2010-07-27 17:53:07Z

2

You should NEVER override alloc.

As for init, which is an instance method, by the way, yes that would be the place where you'd probably want to set up your variables.

answered Jul 27, 2010 at 17:53

Jacob Relkin

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1 Comment

Bet Lamed Over a year ago

I read that a few times now. However, I would like to know, is that a property (haha see what I did? g) of the language, or of the framework? In other words, would @synthesize still work if I don't derive my class from NSObject, and don't tell the compiler to use Foundation?

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