NSString concatenate on creation

Question

I'm trying to concatenate 2 strings assigning the result to a new string.

Normally I would do this way:

NSString * s = [NSString stringWithFormat: @"%@%@", str1, str2];

Now I wish s to be static

static NSString * s = [NSString stringWithFormat: @"%@%@", str1, str2];

but compiler kick me with "Initializer element is not a compile-time..."

Is there any way to do this? I Googled a bit with no results and also I have not found answers on StackOverflow asking the question.

And what about using a short form like (in PHP)

$s = $str1.$str2;

Any help will be appreciated.

EDIT: What i want to achieve is to have a config file like this (in PHP code)

define ("BASE_URL", "mysite.com/");
define ("SERVICE_URL1", BASE_URL."myservice1.php?param1=value1");
define ("SERVICE_URL2", BASE_URL."myservice2.php?param2=value2");

I prefer to have all configurations strings in 1 file and i found usefull static strings in objective c. Just want to put 2 usefull thing together :)

EDIT2: There's no metter if i obtain this with defines, but the NSString way is preferred and i use static just beacause const make me some compilation problems i haven't solved yet

Where is all this code? In a method? Class level static?

Wain
– Wain

2014-02-07 13:11:14 +00:00
Commented Feb 7, 2014 at 13:11 — Wain
– Wain, Commented Feb 7, 2014 at 13:11

Vitaly S. · Accepted Answer · 2014-02-07 14:41:13Z

3

Use this code for creating static s:

static NSString * s = nil;
if (!s)
    s = [NSString stringWithFormat: @"%@%@", str1, str2];

Also for concatenating two string you case use such code: NSString *s = [str1 stringByAppendingString: str2];

UPDATED: You can concat static string by putting them one by one. Example:

#define STR1 @"First part" @" Second part"
#define STR2 @"Third part " STR1
NSLog(@"%@", STR2);

This cole will print Third part First part Second part

edited Feb 7, 2014 at 14:41

answered Feb 7, 2014 at 13:04

Vitaly S.

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6 Comments

Alex75 Over a year ago

why the if(!s) is needed? cannot i simply do s = [NSString stringWithFormat: @"%@%@", str1, str2];?

Alex75 Over a year ago

Ok, and what about the short form? is there any literal way? the problem is that i have all the static strings in an .h file and compiler don't allow me to do if inside

Vitaly S. Over a year ago

@Alex75, are str1 and str2 constants? How do you define them?

Alex75 Over a year ago

@VitalyS. they are static NSString as well. I can also use #define if needed, but i think there is the same problem

Amin Negm-Awad Over a year ago

Your code is not useful. A message is sent, a result is /computed/ at /runtime/, every time it is executed, but you want to have it static? Probably you mismatched static and immutable. If you want to create a string at compile time, look at my answer.

|

Ashutosh · Accepted Answer · 2014-02-07 13:05:17Z

1

I think below lines may help:

NSString *str1 = @"String1";
NSString *str2 = @"String2";
NSString *combinedStr = [str1 stringByAppendingString:str2];

answered Feb 7, 2014 at 13:05

Ashutosh

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1 Comment

Popeye Over a year ago

How does this help? They state they want it to be static so this is incorrect where is the static? -1 I will remove if corrected, and I have tested this it doesn't just mean adding static.

Amin Negm-Awad · Accepted Answer · 2014-02-07 14:17:36Z

1

If you can use a define, it is pretty simple:

#define A @"a"
#define B @"b"
…
static NSString *ab = A B; // or: @"A" @"B"

You can always concatenate string literals with a single space.

But something very important has to happen to use defines. What's wrong with computing it non-static or compute it once?

BTW: You should use dispatch_once() and not if. For the reasons you can search "dispatch_once" on SO.

answered Feb 7, 2014 at 14:17

Amin Negm-Awad

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Comments

Jose Servet · Accepted Answer · 2014-02-07 14:52:30Z

0

If you don't mind compiling Objective-C++ code, you could simply change the extension from .m to .mm, by default XCode compiles according to file type, and this is valid in Objective-C++

answered Feb 7, 2014 at 14:52

Jose Servet

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1 Comment

Alex75 Over a year ago

Really don't know wich are the difference between OBJC and OBJC++ and wich is the advantage to use one instead the other, but for now i'll go with OBJC since this is an almost finished project for my company

Alex75 · Accepted Answer · 2014-02-07 15:10:33Z

0

Solved this way:

#define kBaseURL @"mysite.com/"
static NSString *kServiceUrl1 = kBaseURL @"myservice1.php?param1=value1";
static NSString *kServiceUrl2 = kBaseURL @"myservice2.php?param2=value2";

thanks all.

now the question is wich one i have to accept as right answer? I mean, mine is the solution, but I would never have got there without your help guys

answered Feb 7, 2014 at 15:10

Alex75

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2 Comments

Amin Negm-Awad Over a year ago

Definetly Vitali's: First he init's a static with an if instead of dispatch_once() and then he copied my answer in an update. This has to be honored. ;-)

Alex75 Over a year ago

i have red the answer linked by him and basically is no wrong, but the if and the dispatch_once solutions is for a method usage and not what i need exactly. My solution don't need a method so i'll accept mine, but put an up sign to yours since them was useful :)

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