key-value-coding

I know the string name of a property of an object. How would I go about getting and setting that property using the string? While @weichsel is correct, there is a better way. Use: [anObject valueForKey: @"propertyName"]; and [anObject setValue:value forKey:@"propertyName"]; Obviously, @"propertyName" can be an NSString that is dynamically composed at runtime. This technique is called Key Value Coding and is fundamental to Cocoa. Why this is better is because -valueForKey will do what is necessary to "box" whatever type the property returns into an object. Thus, if the property is of type int ,

Is there any way to access an NSArray element with valueForKeyPath ? Google's reverse geocoder service, for example, returns a very complex data structure. If I want to get the city, right now I have to break it into two calls, like this: NSDictionary *address = [NSString stringWithString:[[[dictionary objectForKey:@"Placemark"] objectAtIndex:0] objectForKey:@"address"]]; NSLog(@"%@", [address valueForKeyPath:@"AddressDetails.Country.AdministrativeArea.SubAdministrativeArea.Locality.LocalityName"]); Just wondering if there's a way to shoehorn the objectAtIndex: call into the valueForKeyPath

I am trying to get key-value-observing to work for an NSMutableArray. Below is the .h file for MyObservee, the observed class: @interface MyObservee : NSObject { @private int someValue; @private NSMutableArray *someArray; } @property (readwrite,assign) int someValue; - (NSMutableArray *)someArray; @end The class MyObserver implements observeValueForKeyPath:ofObject:change:context:. Here is how I add the observer: MyObservee *moe = [[MyObservee alloc] init]; MyObserver *mobs = [[MyObserver alloc] init]; [moe addObserver:mobs forKeyPath:@"someArray" options:(NSKeyValueObservingOptionNew |

A class has a property (and instance var) of type NSMutableArray with synthesized accessors (via @property ). If you observe this array using: [myObj addObserver:self forKeyPath:@"theArray" options:0 context:NULL]; And then insert an object in the array like this: [myObj.theArray addObject:NSString.string]; An observeValueForKeyPath... notification is not sent. However, the following does send the proper notification: [[myObj mutableArrayValueForKey:@"theArray"] addObject:NSString.string]; This is because mutableArrayValueForKey returns a proxy object that takes care of notifying observers.