Cannot pass NSString to DetailViewController

Question

MasterViewController.h

NSString *quality;

MasterViewController.m

#import DetailViewController.h

-(void)viewDidLoad {
    quality = [NSString stringWithFormat:@"string to pass"];

    ...

}

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    if ([[segue identifier] isEqualToString:@"showDetail"]) {
        DetailViewController *detailView = [segue destinationViewController];

        NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];

        theList = [app.listArray objectAtIndex:indexPath.row];

        detailView.theList = theList;

        detailView.streamQuality = quality;

    }
}

DetailViewController.h

@property (nonatomic ,retain) NSString *streamQuality;

DetailViewController.m

@synthesize streamQuality;

NSLog(@"Final: %@", streamQuality);

Output: Most I get "Thread 1: EXC_BAD_ACCESS(code=2, address=0x10)"
or something random like "Final: Copy Audio Address"

However this works fine:

detailView.streamQuality = @"hello";

what is quality ? have you checked its value before passing it ot detailViewController ? — Prashant Nikam, Sep 17 '13 at 10:48
Are you using ARC? If not then stringWithFormat returns autoreleased string, so you need to retain it. Try using: quality = [[NSString stringWithFormat:@"string to pass"] retain];. — Nuzhat Zari, Sep 17 '13 at 11:17

Bhavin · Answer 1 · 2013-09-17T11:45:18.830

1

You should create a property to retain NSString Object quality. For Eg :

@property (nonatomic ,copy) NSString *quality;

and of course you have to synthesize it :

@synthesize quality;

and then you should use this property to set the string. Like this :

self.quality = @"string to pass";

edited Sep 17 '13 at 11:45

answered Sep 17 '13 at 10:44

Bhavin

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same problem again... – Lorenz Sep 17 '13 at 11:02
@Lorenz : On which line, you are getting crash ? – Bhavin Sep 17 '13 at 11:16
0x1f7dd85: movl 16(%edx), %edx - Thread 1: EXC_BAD_ACCESS(code=2, address=0x10) – Lorenz Sep 17 '13 at 11:17
@Lorenz : Have you checked using Break Points ? On which line (from the lines you added in your Question), you are getting crash ? – Bhavin Sep 17 '13 at 11:20
From this: detailView.streamQuality = quality; – Lorenz Sep 17 '13 at 11:22
detailView.streamQuality = @"hello"; works – Lorenz Sep 17 '13 at 11:22
@Lorenz : Try : `quality = [[NSString alloc] initWithFormat:@"string to pass"];` – Bhavin Sep 17 '13 at 11:25
Why Downvote ? At least explain the reason behind the downvote... – Bhavin Sep 17 '13 at 11:36
1

What's the point of creating a string from a literal that has no format? Just use the literal. – Abizern Sep 17 '13 at 11:37
@Abizern : In case if OP wants to use literal with format then he/she has to use "alloc/init" or "retain" the string anyway to eliminate `EXC_BAD_ACCESS`. That's all my Answer is about. – Bhavin Sep 17 '13 at 11:39
In which case the correct answer is more like `self.quality = @"some string";` which uses the memory management semantics of the property. – Abizern Sep 17 '13 at 11:42
@Abizern : Yes, you are right. I edited my Answer now. Is that fine ? – Bhavin Sep 17 '13 at 11:45
Almost - you should be using `copy` for classes that are part of a mutable/immutable class cluster. – Abizern Sep 17 '13 at 11:47
@Abizern : Oh, ya. Thanks for correcting me and `copy`. – Bhavin Sep 17 '13 at 11:48

Cannot pass NSString to DetailViewController

1 Answers1