How do I loop through NSString N number of times?

Question

how do I loop the string 9 times ? (z x c v b n z x c)

NSString *fl = @"zxcvbn";

Can you be more specific? Do you need to go through the characters and if there's less characters then the loop count start appending string to the end from the beginning? — Islam, Nov 22 '15 at 04:28

score 1 · Accepted Answer · edited May 23 '17 at 11:59

1

Here's a fast and dirty snippet:

NSString *string = @"abcdef";
NSString *letter = nil;
int n = 9;
for (int index = 0; index < n; index++) {
    // start over if it's more than the length
    int currentIndex = index % string.length;

    letter = [string substringWithRange:NSMakeRange(currentIndex, 1)];

    NSLog(@"letter: %@", letter);
}

If you want a low-level example with detailed explanation check this out.

edited May 23 '17 at 11:59

Community

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answered Nov 22 '15 at 04:53

Islam

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Instead of the `while` loop, simply do `int currentIndex = index % string.length;`. – rmaddy Nov 22 '15 at 05:14
How can I get index path of letter ? – user5276912 Nov 22 '15 at 05:30
Isn't that `currentIndex`? – Islam Nov 22 '15 at 05:31
index 0 letter: a........ index 6 letter: g again it repeats index 0 letter: a index 1 letter: b how can I know repeated index ? – user5276912 Nov 22 '15 at 05:39
`index` always starts from 0 and `position = index + 1` – Islam Nov 22 '15 at 05:45
Can you explain briefly I am new to coding – user5276912 Nov 22 '15 at 05:59
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/95827/discussion-between-islam-q-and-user5276912). – Islam Nov 22 '15 at 06:11

Rob · Answer 2 · 2015-11-22T05:18:04.103

0

In addition to using substringWithRange (which returns a NSString), you can also use characterAtIndex to get the character value:

NSInteger n = 9;

for (NSInteger index = 0; index < n; index++) {
    unichar character = [fl characterAtIndex:index % fl.length];

    // do something with `character`, e.g.
    //
    // if (character == 'z') { ... } 
}

edited Nov 22 '15 at 05:18

answered Nov 22 '15 at 05:07

Rob

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what if i want loop again ? through the same string I mean second time – user5276912 Nov 22 '15 at 05:09
Use `index % fl.length` in that case, as rmaddy suggested. – Rob Nov 22 '15 at 05:19

How do I loop through NSString N number of times?

2 Answers2