How to use Initializer list in objective C

Question

I have worked on c++, there we used initializer list like below to initialize the constructor of base class.

Derived::Derived(int x):Base(x) { 
    cout << "B's Constructor called";
}

How to acheive the same action in objective C. How to pass value to base (super) class while initlizing. Is it possible?

thanx.

Do you mean the sequence of init method? – Jake Lin Aug 28 '13 at 10:45 — Jake Lin, Aug 28 '13 at 10:45

Puneet Sharma · Answer 1 · 2013-08-28T11:09:31.700

2

Here we use super to call the Base Class Constructor. For example: Lets say we have a base class, and has this initiator method

// Base .h
- (id)initWithName:(NSString *)name;
@property (strong, nonatomic) NSString *name;

// Base.m
- (id)initWithName:(NSString *)name
 {
   self = [super init];
   if(self){
     self.name = name;
   }
  return self
 }

 // Derived.h
- (id)initWithName:(NSString *)name;

// Derived.m
- (id)initWithName:(NSString *)name
 {
   self = [super initWithName:name];
    return self;
 }

// This is how we can create an object of Derived class
Derived *derived = [[Derived alloc]initWithName:@"foo"];

edited Aug 28 '13 at 11:09

answered Aug 28 '13 at 10:50

Puneet Sharma

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So base class do we need to write init methods corresponding to ivars, init:(id)value : (NSString8)... – Newbee Aug 28 '13 at 10:51
No. You can call another super method as well from one init method in Base class. – Puneet Sharma Aug 28 '13 at 10:59
1

I got the same doubts... it helps... :) – Feroz Aug 28 '13 at 11:13

score 0 · Answer 2 · edited Oct 13 '14 at 19:57

0

- (instancetype)init {
    if (self = [super init]) {
       // your code here
    }
    return self;
}

edited Oct 13 '14 at 19:57

Nate Symer

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answered Aug 28 '13 at 10:48

Krishna Kumar

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Jake Lin · Answer 3 · 2013-08-28T10:57:38.857

0

In Objective-C, there is no constructor, the subclass needs to call parent's class's init method explicitly. like [super init];

Here is a good article to describe the initialiser of Objective C objects. Object Initialization

edited Aug 28 '13 at 10:57

answered Aug 28 '13 at 10:49

Jake Lin

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score 0 · Accepted Answer · answered Aug 28 '13 at 10:53

0

We use [super init]; to initialize all your super classes. It does what you require.

answered Aug 28 '13 at 10:53

iOS

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how to pass value while initilizing? – Newbee Aug 28 '13 at 10:53
Create custom initializer. – iOS Aug 28 '13 at 11:01
The link may help you - http://stackoverflow.com/questions/6084802/passing-parameters-to-a-custom-class-on-initialization – iOS Aug 28 '13 at 11:02

How to use Initializer list in objective C

4 Answers4