issue when retrieving elements from array of objects- objective C

Question

I have a class Person with variables name,age,local and about, i added values of person object to a mutable array as shown:

Person *myPerson=[[Person alloc]init];
NSMutableArray *personArray=[[NSMutableArray alloc]init];

myPerson.name=namefield;    //'namefield' retrieved from db
myPerson.age=agefield;      //'agefield' retrieved from db
myPerson.local=locfield;    //'locfield' retrieved from db
myPerson.about=aboutfield;  //'aboutfield' retrieved from db

[personArray addObject:myPerson];

and I have problem when trying to print out the elements using below code;which shows last element repeatedly,

for (int i = 0; i < [personArray count]; i++){
    Person * p = [personArray objectAtIndex:i];
    NSLog(@"name %@",p.name);
    NSLog(@"age %@",p.age);      
}

hope you will be kind to me as I am a new guy to iPhone development. Thanks.

possible duplicate of How can I add new object instance in a mutable array using same object reference as the previous one, Array addobject is changing all array values instead of just appending — jscs
– jscs, Commented Feb 25, 2013 at 6:48
Are you using any loop to insert multiple objects into array? If yes then how have you implemented that loop? — Exploring
– Exploring, Commented Feb 25, 2013 at 6:51
possible duplicate of Array addObject is changing all array values instead of just appending — rmaddy
– rmaddy, Commented Feb 25, 2013 at 6:52

Naimish Karia · Accepted Answer · 2013-02-25 06:52:19Z

3

you can write code like this

NSMutableArray *personArray=[[NSMutableArray alloc]init];
for(int i=o;i<noOfRecords;i++)
{
    Person *myPerson=[[Person alloc]init];
    myPerson.name=namefield;    //'namefield' retrieved from db
    myPerson.age=agefield;      //'agefield' retrieved from db
    myPerson.local=locfield;    //'locfield' retrieved from db
    myPerson.about=aboutfield;  //'aboutfield' retrieved from db

    [personArray addObject:myPerson];
    [myPerson release];
}

Then retrieve array this may be helpful because you are fetching only last row

release if ARC is not enabled otherwise no need to release

answered Feb 25, 2013 at 6:52

Naimish Karia

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2 Comments

Naimish Karia Over a year ago

yes that is my point but i come to know later that you also post same

devluv Over a year ago

yeah sure ..no issue, things should be clear to him, and that is all that matters :) :) and you provide a nice code showing him cheers

devluv · Accepted Answer · 2013-02-25 06:52:04Z

2

Person *myPerson=[[Person alloc]init]; this line, it seems you have written this line outside the for loop where you are adding objects. As such there is only one instance of person class being there represented by all objects of the array. put that line inside the for loop, so that at every iteration a new person object is added to the array.

answered Feb 25, 2013 at 6:52

devluv

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Comments

lnafziger · Accepted Answer · 2013-02-25 06:49:20Z

2

It looks like you are re-using myPerson. When you add an object to an array, it does not create a copy of it. Instead, it just stores a reference to the object, therefore when you change it later it changes ALL of the references pointing to it.

Change this line:

[personArray addObject:myPerson];

To this line:

[[personArray addObject:myPerson] copy];

in order to add a copy of your person to the array.

answered Feb 25, 2013 at 6:49

lnafziger

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Comments

P.J.Radadiya · Accepted Answer · 2016-08-04 06:51:31Z

0

Person *myPerson=[[Person alloc]init];
NSMutableArray *personArray=[[NSMutableArray alloc]init];

myPerson.name=namefield;    //'namefield' retrieved from db
myPerson.age=agefield;      //'agefield' retrieved from db
myPerson.local=locfield;    //'locfield' retrieved from db
myPerson.about=aboutfield;  //'aboutfield' retrieved from db

for (int i = 0; i < [personArray count]; i++) 
{
    [personArray addObject:myPerson];
    NSLog(@"name %@",p.name);
}

Try this...

edited Aug 4, 2016 at 6:51

P.J.Radadiya

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answered Feb 25, 2013 at 6:59

Praveen

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