Geocoder throwing odd exception - ios

Question

I have a method that is triggered on the press of a button. This is most of the implmentation:
[self.placeDictionary setValue:#"166 Bovet Rd" forKey:#"Street"];
[self.placeDictionary setValue:#"San Mateo" forKey:#"City"];
[self.placeDictionary setValue:#"CA" forKey:#"State"];
[self.placeDictionary setValue:#"94402" forKey:#"ZIP"];
CLGeocoder *geocoder = [[CLGeocoder alloc] init];
[geocoder geocodeAddressDictionary:self.placeDictionary completionHandler:^(NSArray *placemarks, NSError *error) {
if([placemarks count]) {
CLPlacemark *placemark = [placemarks objectAtIndex:0];
CLLocation *location = placemark.location;
CLLocationCoordinate2D coordinate = location.coordinate;
PFGeoPoint* userLocation = [PFGeoPoint geoPointWithLatitude:coordinate.latitude longitude:coordinate.longitude];
NSLog(#"%f,%f", userLocation.latitude, userLocation.longitude);
} else {
NSLog(#"location error");
return;
}
}];
However, I am getting the following exception:
*** WebKit discarded an uncaught exception in the webView:shouldInsertText:replacingDOMRange:givenAction: delegate: <NSUnknownKeyException> [<__NSDictionaryI 0x873a3c0> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key Street.
I have absolutely no idea what this exception means. Could someone help me understand why it is producing this?

Answer 1

First off, you are trying to add objects to an immutable dictionary. The part of the exception beginning [<__NSDictionaryI 0x873a3c0> setValue:forUndefinedKey: gives a class name of __NSDictionaryI, which is an immutable member of the NSDictionary class cluster - so you cannot add any objects to it at run-time. You need to ensure that self.placeDictionary is assigned to an NSMutableDictionary instance before this code is called.
Unfortunately, you are also using the wrong method to add the objects - you're using setValue:forKey: instead of setObject:forKey:. Since this method is part of the NSKeyValueCoding informal protocol, you're not stopped from doing this at compile time. You should instead use setObject:forKey: which is the correct method to set key-value pairs on an NSMutableDictionary. After you correct the first issue, replace the setValue:forKey: calls with setObject:forKey:, for example:
[self.placeDictionary setObject:#"San Mateo" forKey:#"City"];