Xcode adding more than one object to NSMutableArray replaces previous

Question

Keep finding similar questions here, but can't find this one

I want to put several objects into an NSMutableArray, and of course be able to retrieve them.

I can put individual strings (First line, Second Line, etc) into the array (as objects), and can see in debugger that they are all being stored - can retrieve them too.

(I don't actually need to put these individual strings in - I only need to put in my "Person" objects. Just thought it might help me to see what does work in terms of moving forward in the NSMutableArray)

Person *aPerson = [[Person alloc] init];        

NSMutableArray *myArray = [[NSMutableArray alloc] init];        
[myArray addObject:@"First line"];        
[myArray addObject:@"Second line"];        
[myArray addObject:@"Third line"];        
[myArray addObject:@"Fourth line"];        
[myArray addObject:@"Fifth line"];

When I put ONE object into the same array, it goes in fine.

aPerson.firstName = @"Jasper"; // Should be sixth        
aPerson.lastName = @"John";        

[myArray addObject:aPerson];

In the debugger when stopping at above point I see the "Jasper John" info in a Person object in the NSMutableArray .... But when I put another object into that NSMutableArray, it replaces the last object - it's as those I didn't advance through the NSMutableArray.

aPerson.firstName = @"Izzie";// Should be seventh         
aPerson.lastName = @"TheKitty";        
[myArray addObject:aPerson];        

aPerson.firstName = @"Roxie";        
aPerson.lastName = @"The Pup";        
[myArray addObject:aPerson];        // Should be eighth

When stopping at above point, I just get "Roxie The Pup" for all 3 objects in the NSMutable Array - though my original 5 strings are still filling up the buckets at the beginning.

BTW 1 - am not doing what the following person did - who is reinitializing his NSMutableArray repeatedly stackoverflow.com/questions/11808720/… 2- I did declare a property for the NSMutableArray I"m using in the .h file associated with this test 3- My test is running inside a standard viewDidLoad method — LaurelS
– LaurelS, Commented Oct 30, 2015 at 19:42

Matt · Accepted Answer · 2015-11-14 10:48:58Z

0

Oh got it!

When I was adding my objects, I was really adding a POINTER to the object And since I was using 'aPerson' object, I was simply changing the contents of the same object, as far as the compiler was concerned. So I was updating the contents of that pointer, every time I did an addObject

Person *aPerson2 = [[Person alloc] init];    
aPerson2.firstName = @"Izzie";// Should be seventh
aPerson2.lastName = @"TheKitty";
[myArray addObject:aPerson2];

Person *aPerson3 = [[Person alloc] init];

aPerson3.firstName = @"Roxie";// Should be eightth
aPerson3.lastName = @"The Pup";
[myArray addObject:aPerson3];

edited Nov 14, 2015 at 10:48

Matt

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answered Oct 30, 2015 at 20:59

LaurelS

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1 Comment

Matt Over a year ago

Please note you seem to have (at least) 3 accounts; stackoverflow.com/users/638736/laurel-shimer, stackoverflow.com/users/5508643/laurels and stackoverflow.com/users/430053/laurels. See stackoverflow.com/help/merging-accounts to see how you can merge these accounts (if you want to).

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