CODEWITHSUNDEEP
objective-ciosarraysstring
Codeguy007
Codeguy007

Reputation: 891

Concatenation of String with Array elements in Objective-C

Can someone one explain to me why this code doesn't work? I have no problem sending the elements of an array to NSLog but they don't seem to be appending to the string. Do I have to cast the array elements to a string?

    success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
        NSArray *dataarray=[JSON valueForKey:@"Data"];
        NSLog(@"Response: %@", [JSON valueForKeyPath:@"Status"]);
        NSString* output = [NSString stringWithFormat:@"response: %@",[JSON valueForKeyPath:@"Status"]];
        int x;
        for (x=0; x<[dataarray count]; x++) {
            NSLog(@"%d : %@",x, [dataarray objectAtIndex:x]);
            [output stringByAppendingFormat:@" %@ ",[dataarray objectAtIndex:x]];
        }

        //NSLog(@"%@", JSON);
        NSLog(@"%@", output);
        self.outPut2.text=output;    }

Upvotes: 2

Views: 3270

Answers (3)

Sixten Otto
Sixten Otto

Reputation: 14816

Your output variable is an immutable NSString. -stringByAppendingFormat: doesn't append the new string in place, it returns a new string value that is the concatenation of the two original strings. You need to assign that value back to output.

In the alternative, make output an NSMutableString, and then you can do the concatenation in place with -appendFormat:.

Upvotes: 2

jere
jere

Reputation: 4304

You output variable is set to be an inmutable string. So you can't directly add any content to it. You can create a new string using it's content and reassign it to itself, but you can't append new content.

You should try using NSMutableString and appendFormat or appendString

        NSMutableString* output = [NSMutableString stringWithFormat:@"response: %@",[JSON valueForKeyPath:@"Status"]];
        int x;
        for (x=0; x<[dataarray count]; x++) {
            NSLog(@"%d : %@",x, [dataarray objectAtIndex:x]);
            [output appendFormat:@" %@ ",[dataarray objectAtIndex:x]];
        }

Upvotes: 1

Ismael
Ismael

Reputation: 3937

The function

 [output stringByAppendingFormat:@" %@ ",[dataarray objectAtIndex:x]];

returns a NEW string, without modifying the original, and you are not storing it anywhere. You should go like this:

output = [output stringByAppendingFormat:@" %@ ",[dataarray objectAtIndex:x]];

Upvotes: 3

Related Questions