How to change a value in a two dimensions NSMutableArray?

Question

I'm new to OC.
In Swift, it's really easy to change a value in a two dimensions array. Just like this a[0][0] = "1"

But I'm really confused now about how to do it in OC.
Thank you for any advice.

self.infos = 
[NSMutableArray arrayWithObjects: [NSMutableArray arrayWithObjects:@"11", @"22", @"33", @"44", @"55", @"66", nil], 
[NSMutableArray arrayWithObjects:@"aa", nil], nil];

For example. how to set aa to bb?

BTW, is it right way to declare infos in @interface?

@property (strong, nonatomic) NSMutableArray* infos;

infos[1] is a NSArray, not a NSMutableArray Is they are indeed mutable, then you can do self.infos[1][0] = @"bb". It's missing a * in @property (strong, nonatomic) NSMutableArray *infos; (XCode should throw an error) — Larme
– Larme, Commented Dec 14, 2017 at 12:17

Shehata Gamal · Accepted Answer · 2017-12-14 12:25:07Z

3

Try simple

   self.infos[1][0] = @"newValue";

or Complex

  NSArray*fr = [self.infos objectAtIndex:1];

 [fr replaceObjectAtIndex:0 withObject:@"newValue"];

edited Dec 14, 2017 at 12:25

answered Dec 14, 2017 at 12:17

Shehata Gamal

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Mohamad Bachir Sidani · Accepted Answer · 2017-12-14 12:18:20Z

0

BTW, you can actually write this:

infos[1][0] = @"bb";

answered Dec 14, 2017 at 12:18

Mohamad Bachir Sidani

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3 Comments

JsW Over a year ago

Oh god! It's Great! But why there are so many complicated methods for accessing?(like remove, replace...)

Mohamad Bachir Sidani Over a year ago

Glad it helped! The reason might be that Objective C deals with pointers not only objects (unlike swift). If you think this is the right answer please mark it as correct Thanks!

JsW Over a year ago

Thanks. But it seems sh_Khan answered a little bit earlier. Thanks again.

J.Hunter · Accepted Answer · 2017-12-14 12:24:50Z

0

Like this：

    NSMutableArray *infos = [NSMutableArray arrayWithObjects:
                         [NSMutableArray arrayWithObjects:@"11", @"22", @"33", @"44", @"55", @"66", nil],
                         [NSMutableArray arrayWithObjects:@"aa", nil],
                         nil];

[infos[0] setObject:@"1" atIndexedSubscript:0];

or

infos[0][1] = @"2";

answered Dec 14, 2017 at 12:24

J.Hunter

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