how to add NSString from loop in NSMutableArray

Question

I want to add NSString Name in NSmutableArray but I dont know about that. I get 5 NSString name from url in wamp server and I want add these names in NSMutableArray.

this is my code but do not work!!! :

    NSMutableArray *file;
for (int j=0; j < 5; j++) {
        NSString *fileName = [[NSString alloc]initWithContentsOfURL:[NSURL URLWithString:[NSString stringWithFormat:@"http://192.168.1.101/janatan/filemanager.php?dir=root&file=%d&name",j]]];
        NSLog(@"%@",fileName);
        [file addObject:fileName]  //right???
    }

alloc]init]; your NSMutableArray.

Bonnie
– Bonnie

2013-04-16 08:23:22 +00:00
Commented Apr 16, 2013 at 8:23 — Bonnie
– Bonnie, Commented Apr 16, 2013 at 8:23
Do you like to add same filename for 5 times?

jkk
– jkk

2013-04-16 08:38:00 +00:00
Commented Apr 16, 2013 at 8:38 — jkk
– jkk, Commented Apr 16, 2013 at 8:38

Krishnabhadra · Accepted Answer · 2013-04-16 08:18:58Z

4

You are not allocating NSMutableArray

NSMutableArray *file = [[NSMutableArray alloc] initWithCapacity:5];

If you are not sure about the number of elements gets added to array beforehand, you can use

NSMutableArray *file = [[NSMutableArray alloc] init];

answered Apr 16, 2013 at 8:18

Krishnabhadra

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Comments

Vladimir Kaltyrin · Accepted Answer · 2013-04-19 11:14:27Z

Firstly, the NSMutableArray must be allocated.

Secondly, the using of magic numbers must be avoided.

Next, the readability of code should be improved by replace

NSString *fileName = [[NSString alloc]initWithContentsOfURL:[NSURL URLWithString:[NSString stringWithFormat:@"http://192.168.1.101/janatan/filemanager.php?dir=root&file=%d&name",j]]];

to something more convenient. Moreover, the memory here is allocated but never released.

Your code may be as follows:

const int numberOfFiles = 5;
NSMutableArray *file = [NSMutableArray array]
for(int i = 0; i < numberOfFiles; ++i){
      NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:@"http://192.168.1.101/janatan/filemanager.php?dir=root&file=%d&name", i]];
      NSString *fileName = [NSString stringWithContentsOfURL:url encoding:NSUTF8StringEncoding error:nil];
      [file addObject:fileName];
 }

But here are we can find some problems. For example if url is changed on server-side you'd rewrite the code. If the number of elements is changed it's the same. So it would be good to find a way to avoid this kind of dependence.

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