retrieving string from NSDictionary

Question

I'm working on the following function:

-(void)logResults:(NSDictionary *)results {
    NSMutableString *logString = [[NSMutableString alloc]init];
    for (NSString *key in results) {
        if([key isEqualToString:@"index"]){
            NSString *string = [[NSString alloc]initWithString:[results objectForKey:key]];
            string = [string stringByReplacingOccurrencesOfString:@"\n" withString:@""];
            [results setValue:string forKey:key];
        }
        NSLog(@"KEY: %@, VALUE: %@", key, [results objectForKey:key]);
        [logString appendFormat:@"|%@ = %@ \n", key, [results objectForKey:key]];
    }
    self.logInfo.text = [logString stringByAppendingString:self.logInfo.text];
}

problem lies within the if, I get the following error: [_NSArrayM length] unrecognised sel...

I was first attempting to use following expression for the if's work:

//[results setValue:[((NSString *)[results objectForKey:key]) stringByReplacingOccurrencesOfString:@"\n" withString:@""] forKey:@"index"];

which resulted in:

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSArrayM stringByReplacingOccurrencesOfString:withString:]

`string` might be a `NSArray` hence the `[__NSArrayM stringByReplacingOccurrencesOfString:withString:]`. Check to see if `string` actually is getting the string that you want. — somtingwong, Jul 16 '15 at 18:10
@user1813076 it is. the line: [logString appendFormat:@"|%@ = %@ \n", key, [results objectForKey:key]]; has been working fine. I am only doing this to trim a string i was already getting properly. btw, even the initial NSString *string = [[NSString alloc]initWithString:[results objectForKey:key]]; crashes, which i find very weird since the first-mentioned expression (in this comment) works, and they are both treating strings. I did also try to make a cast to NSString — DevilInDisguise, Jul 16 '15 at 18:20
At what line exactly does it crash and what is the exact error message for the code block? — luk2302, Jul 16 '15 at 18:20
@DevilInDisguise please show your NSDictionary data, it problem about you are fetch wrong way data from it. — Pravin Tate, Jul 16 '15 at 18:22
@luk2303 NSMutableString *string = [[NSMutableString alloc]initWithString:(NSString *)[results objectForKey:key]]; this initial line causes a crash. Referring to me above comment I think this is weird as a latter expression works. ERROR: erminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSArrayM length]: unrecognized selector sent to instance 0x17005ffb0' — DevilInDisguise, Jul 16 '15 at 18:23
Add inside your if an additional if, something like `if ([[results objectForKey:key] isKindOfClass [NSString class]]) {}` and some NSLog into `else` statement to see if it's really NSString. — teamnorge, Jul 16 '15 at 18:24
@teamnorge [logString appendFormat:@"|%@ = %@ \n", key, [results objectForKey:key]] would not execute if it wasn't a string. — DevilInDisguise, Jul 16 '15 at 18:34
also `[logString appendFormat:@"|%@ = %@ \n", key, [results objectForKey:key]]` still executes if it wasn't a string. Short description why is [here](http://stackoverflow.com/questions/3396336/print-array-in-objective-c) — somtingwong, Jul 16 '15 at 18:39
@DevilInDisguise, you could also check if your `[key isKindOfClass [NSString class]]` before comparing is it is equal to `@"index"`. — teamnorge, Jul 16 '15 at 18:47
@user1813076 you are right. can i check the specific class without testing isMemberOfClass, conformsToProtocol on different types? — DevilInDisguise, Jul 16 '15 at 18:52
@user1813076 u should post that as an answer, valueForKey or objectForKey both works(don't know the difference rly). Does it make sense that you are allowed to assign nsstring instances non-string types? this is what got me — DevilInDisguise, Jul 16 '15 at 19:14
@DevilInDisguise one more thing I did not noticed initially, your `results` is of type `(NSDictionary *)` not `(NSMutableDictionary *)` and you attempt to setValue on non mutable object. — teamnorge, Jul 16 '15 at 19:16
@teamnorge [setValue forKey:] is available for NSDictionary, at least pops up as suggestion in Xcode.. I got what i wanted another way now, but thx for your input. Amazing how someone just down voted myq uestion just now... ppl are funny lol. cheers — DevilInDisguise, Jul 16 '15 at 21:51

score 0 · Accepted Answer · answered Jul 16 '15 at 19:30

0

Your [results objectForKey:key]]; is returning an array which is causing all of your crashes. To create a NSString from the array use [results valueForKey:@"description"] componentsJoinedByString:@""];

answered Jul 16 '15 at 19:30

somtingwong

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so it turned out that the json i was parsing into a string, thinking it was a string, I could just handle the objects and arrays instead of doing string analysing lol.... thx for the help! – DevilInDisguise Jul 16 '15 at 19:40

retrieving string from NSDictionary

1 Answers1