StackOverflow2013

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POUndefined key when iterating through NSDictionary
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copied!<p>I am pretty new to iPhone/Objective-c programming. I'm struggling with an issue that doesn't make sense to me. I am writing an app that, as part of the code, will consume restful services. The method I am writing to make Post calls, using the ASIHttpRequest library, looks like this:</p> <pre><code>- (NSString *) httpPostStringResponseUrl:(NSURL *)url:(NSDictionary *)args{ ASIFormDataRequest *request = [[[ASIFormDataRequest alloc] initWithURL:url] autorelease]; NSArray *keys = [args allKeys]; NSEnumerator *e = [args keyEnumerator]; NSString* object; while (object = [e nextObject]) { NSLog(@"Adding to args key: %@", object); [request setPostValue:[keys valueForKey:object] forKey:object]; } NSLog(@"Starting http POST request"); [request startSynchronous]; NSString *response = [request responseString]; return response; } </code></pre> <p>The idea is to pass in a dictionary of arguments and their values, and use them as the arguments to the POST request. However, when I run this code I get an NSUnknownKeyException. </p> <p>This doesn't make sense to me. The only access to the dictionary I am doing is using the keys provided by the iterator. So, how can they be part of the iterator and not be valid keys?</p> <p>For completeness, here is the code where I call the above function:</p> <pre><code>NSMutableDictionary *params = [[[NSMutableDictionary alloc] init] autorelease]; NSURL *url = [[[NSURL alloc] initWithString:@"http://myURL"] autorelease]; [params setValue:@"user" forKey:@"Username"]; [params setValue:@"1234" forKey:@"Password"]; NSString *response = [web httpPostStringResponseUrl:url :params]; NSLog(@"Response is \"%@\"", response); </code></pre>

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