Sparrow Forum

1. 

   Doolali
   

   Senior Bird
   Joined: Aug '11
   Posts: 134

   

   Doolali

   Senior Bird
   Joined: Aug '11
   Posts: 134

   So i'm trying to parse some data, it all seemed to be going ok, but i have an odd error.

   I'm getting EXC_BAD_ACCESS not really sure why, I'm new to using NSString so..

   First code crashes, second doesn't:

   // crashes
   bool nameTime = true;
       NSString *temp;
       int i = 0;
       while([info characterAtIndex:i] != '!')
       {
           [temp stringByAppendingString:[NSString stringWithFormat:@"%C", [info characterAtIndex:i]]];
           i++;
           printf("%d\n", i);
       }
    
   // doesnt crash (no bool)
       NSString *temp;
       int i = 0;
       while([info characterAtIndex:i] != '!')
       {
           [temp stringByAppendingString:[NSString stringWithFormat:@"%C", [info characterAtIndex:i]]];
           i++;
           printf("%d\n", i);
       }

   Posted 6 years ago #
2. 

   Chris
   

   Moderating Bird
   Joined: Jul '11
   Posts: 126

   

   Chris

   Moderating Bird
   Joined: Jul '11
   Posts: 126

   Try replacing

   bool nameTime = true;

   by

   BOOL nameTime = YES;

   Posted 6 years ago #
3. 

   Doolali
   

   Senior Bird
   Joined: Aug '11
   Posts: 134

   

   Doolali

   Senior Bird
   Joined: Aug '11
   Posts: 134

   Nope didn't work, might be worth adding that even if i change the bool to an int, i still get the error.

   Posted 6 years ago #
4. 

   Chris
   

   Moderating Bird
   Joined: Jul '11
   Posts: 126

   

   Chris

   Moderating Bird
   Joined: Jul '11
   Posts: 126

   Where do you use this bool?
   EXC_BAD_ACCESS usually happens when you trying to access some object that had been already released.

   Posted 6 years ago #
5. 

   Doolali
   

   Senior Bird
   Joined: Aug '11
   Posts: 134

   

   Doolali

   Senior Bird
   Joined: Aug '11
   Posts: 134

   at the moment nowhere... The problem is surely with temp, not the bool.
   I've just read in the error log on the left,

   temp = (NSString *) 0x1 <invalid address>

   Posted 6 years ago #
6. 

   Chris
   

   Moderating Bird
   Joined: Jul '11
   Posts: 126

   

   Chris

   Moderating Bird
   Joined: Jul '11
   Posts: 126

   Sorry, but I don't have how to test it now... But try this:

    
   BOOL nameTime = YES;
       NSString *temp;
       for(int i = 0 ;[info characterAtIndex:i] != '!'; i++)
       {
           [temp stringByAppendingString:[NSString stringWithFormat:@"%C", [info characterAtIndex:i]]];
           NSLog("%i", i);
       }

   Is info a NSString also? Could you post the code where you declare it?

   Posted 6 years ago #
7. 

   Chris
   

   Moderating Bird
   Joined: Jul '11
   Posts: 126

   

   Chris

   Moderating Bird
   Joined: Jul '11
   Posts: 126

   When you call

   [info characterAtIndex:i]

   You must be shure that the variable "i" is not bigger than the NSString length.

   Posted 6 years ago #
8. 

   Shilo
   

   Master Sparrow
   Joined: Dec '10
   Posts: 988

   

   Shilo

   Master Sparrow
   Joined: Dec '10
   Posts: 988

   EXC_BAD_ACCESS occurs when you access a pointer that has been released or is pointing towards an invalid location. The reason why it crashes on temp is because you are trying to access temp which is neither initialized nor declared explicitly as nil. If you declare a pointer without setting it as nil or allocating it, there is a chance that it will point towards a random location.

   So the correct way would be to do:

   NSString *temp = @"";

   Also make sure "info" is not being released too soon.

   Posted 6 years ago #
9. 

   Doolali
   

   Senior Bird
   Joined: Aug '11
   Posts: 134

   

   Doolali

   Senior Bird
   Joined: Aug '11
   Posts: 134

   Point goes to shilo =p cheers for the explanation aswell! And thanks for the help chris.

   Posted 6 years ago #
10. 

    Chris
    

    Moderating Bird
    Joined: Jul '11
    Posts: 126

    

    Chris

    Moderating Bird
    Joined: Jul '11
    Posts: 126

    Shilo rules! xD

    Question:
    

    NSString *temp = nil;

    would work as well?

    Posted 6 years ago #
11. 

    freerunnering
    

    Moderating Bird
    Joined: Jun '10
    Posts: 395

    

    freerunnering

    Moderating Bird
    Joined: Jun '10
    Posts: 395

    No because if it's nil any message sent to it is ignored.
    So with temp = nil; it won't crash but:

    [temp stringByAppendingString:[NSString stringWithFormat:@"%C", [info characterAtIndex:i]]];

    might as well be commented out.

    Posted 6 years ago #
12. 

    Chris
    

    Moderating Bird
    Joined: Jul '11
    Posts: 126

    

    Chris

    Moderating Bird
    Joined: Jul '11
    Posts: 126

    Got it!
    Thanks!

    Posted 6 years ago #
13. 

    Doolali
    

    Senior Bird
    Joined: Aug '11
    Posts: 134

    

    Doolali

    Senior Bird
    Joined: Aug '11
    Posts: 134

    I have another small question, im using the line below to retrieve data from a website: it all works fine except it gives me a yellow caution saying its deprecated, is there something else i should be using?

    info = [NSString stringWithContentsOfURL:[NSURL URLWithString:escapedURL]];

    Posted 6 years ago #
14. 

    Shilo
    

    Master Sparrow
    Joined: Dec '10
    Posts: 988

    

    Shilo

    Master Sparrow
    Joined: Dec '10
    Posts: 988

    You can find the suggested equivelent methods here: http://developer.apple.com/library/ios/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/DeprecationAppendix/AppendixADeprecatedAPI.html#//apple_ref/occ/clm/NSString/stringWithContentsOfURL:.

    Posted 6 years ago #
15. 

    Doolali
    

    Senior Bird
    Joined: Aug '11
    Posts: 134

    

    Doolali

    Senior Bird
    Joined: Aug '11
    Posts: 134

    Cheers for that got it all sorted!

    Posted 6 years ago #

RSS feed for this topic

Reply

You must log in to post.