What is id in Objective C?

Tarun Kumar 2041 15 Jul 2015

Tarun Kumar

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1 Answers

Tarun Kumar 15 Jul 2015

id can hold pointer of any kind of object.
syntax:

id newPointer = somepointer;
e.g.

NSString *str = @"karm";
id newStr = str;

It will work perfectly. Here is something you should note that id keyword is not followed by an *, its because id already knows that it is a pointer.

We use this while return objects from the derived class while we overrige the init method as shown below:

-(id)init 
  {
    if (self = [super init])
    {
       someIVarObject = [SomeClass alloc] init];
    }
    return self;
  }

Here we return id because somebody can initialize an object like this.
BaseClass *base = [[DerivedClass alloc] init];
In this case, we want to make sure we have the right pointer returned from the init method.
Summary:

id is a reserved keyword.
It can hold pointer to any object.
It can hold pointer to nil.

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What is id in Objective C?

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