Adding a instance of `NSMutableArray` into `NSArray` objects

Question

I am adding a instance of NSMutableArray in NSArray.

Code:

    NSMutableArray *var2=[[NSMutableArray alloc]init];
    [var2 addObject:@"c++"];
    NSArray *var1=[[NSArray alloc]initWithObjects:var2, nil];
    [var2 addObject:@"c"];
    [var2 addObject:@"wt"];
    NSLog(@"Mutable%@",var2);
    NSLog(@"Simple%@",var1);

Output:

2015-07-29 14:51:10.494 Kom4[3249:60b] Mutable(
    "c++",
    c,
    wt
)
2015-07-29 14:51:10.496 Kom4[3249:60b] Simple(
        (
        "c++",
        c,
        wt
    )
)

Question: NSArray size will be fixed at the time of initialisation. But we are passing instance of NSMutableArray .It is of flexible size. How is this showing the output?

trojanfoe · Accepted Answer · 2015-07-29 09:41:51Z

1

No, the NSArray will remain fixed (it's immutable) and isn't flexible at.

This is because you are holding a reference to the object and a reference never changes in size, regardless of how large the referenced object gets.

answered Jul 29, 2015 at 9:41

trojanfoe

123k23 gold badges219 silver badges249 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Lepidopteron · Accepted Answer · 2015-07-29 09:42:30Z

1

you have initialized your NSArray with an object, so the array holds a pointer to that object.

If you want to initialize it with the mutable array's objects, use "initWithArray:" instead: https://developer.apple.com/library/prerelease/ios/documentation/Cocoa/Reference/Foundation/Classes/NSArray_Class/index.html

Your output just shows the same: An Array, which has exactly one object: another array with 3 Elements:

In Short:

@[
    @[
         @"c++",
         @"c",
         @"wt",
     ]
]

answered Jul 29, 2015 at 9:42

Lepidopteron

6,1855 gold badges45 silver badges55 bronze badges

Comments

gnasher729 · Accepted Answer · 2015-07-29 09:50:09Z

0

Your NSArray is fixed. It contains your NSMutableArray and nothing else; that NSMutableArray cannot be removed, nothing else can be added to the NSArray, so it will contain the NSMutableArray and nothing else until the end of its lifetime.

That doesn't mean you cannot change the NSMutableArray. It's always the same array, but with different contents. That's what your NSLog shows; the NSArray contains the same object, but with different contents.

answered Jul 29, 2015 at 9:50

gnasher729

53k5 gold badges83 silver badges106 bronze badges

Collectives™ on Stack Overflow

Adding a instance of `NSMutableArray` into `NSArray` objects

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related