Cocoa - Determining a class' properties at run time

Question

Is this simple? I'm actually trying to monitor if an object changes (to determine if I should save it). Currently I just have an array in the object with a list of all of it's readwrite properties, then I loop through it after the object is created and add observers:

for ( NSString *observer in _observers ){
    [self addObserver: self forKeyPath: observer options: NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld context: nil];
}

It works, but if you forget to add a property to the array, obviously the observer won't be called. Does anyone know how I can just determine the object's properties at runtime? I was thinking it may be around respondsToSelector: but I haven't been able to find much on the subject.

Thanks in advance!

Answer 1

Properties of an object, after they have been synthesized, behave almost like ordinary object's methods, so you can do following check

if ([myObject respondsToSelector: @selector(propertyName)]) {
    // your code here
}

Or if you want to use strings as selector's name:

if ([myObject respondsToSelector: NSSelectorFromString(@"propertyName")]) {
    // your code here
}

Here propertyName is a getter (it's signature name exactly corresponds to your declared property name), so if you want to check for setter presence, you should add additional expression:

[myObject respondsToSelector: @selector(setPropertyName:)])