I'm trying to dynamically determine the type of a property in Objective-C. Based on what I have read on this site and elsewhere, I believe I am doing the right thing. However, my code isn't working.

The code snippet below demonstrates the problem. Attempting to get the property information for "backgroundColor" and "frame", both of which are valid properties of UIView, fails (class\_getProperty() returns NULL):

```
id type = [UIView class];        
objc_property_t backgroundColorProperty = class_getProperty(type, "backgroundColor");
fprintf(stdout, "backgroundColorProperty = %d\n", (int)backgroundColorProperty); // prints 0

objc_property_t frameProperty = class_getProperty(type, "frame");
fprintf(stdout, "frameProperty = %d\n", (int)frameProperty); // prints 0

```

Enumerating the properties as described [here](https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/ObjCRuntimeGuide/Articles/ocrtPropertyIntrospection.html) doesn't produce the expected results, either. The following code:

```
NSLog(@"Properties for %@", type);
unsigned int outCount, i;
objc_property_t *properties = class_copyPropertyList(type, &outCount);
for (i = 0; i < outCount; i++) {
    objc_property_t property = properties[i];
    fprintf(stdout, "%s %s\n", property_getName(property), property_getAttributes(property));
}

```

generates this output:

```
2012-03-09 13:18:39.108 IOSTest[2921:f803] Properties for UIView
caretRect T{CGRect={CGPoint=ff}{CGSize=ff}},R,N,G_caretRect
gesturesEnabled Tc,N
deliversTouchesForGesturesToSuperview Tc,N
skipsSubviewEnumeration Tc,N
viewTraversalMark Tc,N
viewDelegate T@"UIViewController",N,G_viewDelegate,S_setViewDelegate:
inAnimatedVCTransition Tc,N,GisInAnimatedVCTransition
monitorsSubtree Tc,N,G_monitorsSubtree,S_setMonitorsSubtree:
backgroundColorSystemColorName T@"NSString",&,N,G_backgroundColorSystemColorName,S_setBackgroundColorSystemColorName:
userInteractionEnabled Tc,N,GisUserInteractionEnabled
tag Ti,N,V_tag
layer T@"CALayer",R,N,V_layer

```

Documented properties such as "backgroundColor", "frame", and others are missing, whereas undocumented properties like "caretRect" and "gesturesEnabled" are included.

Any help would be very much appreciated. In case it is relevant, I'm seeing this behavior on the iOS simulator. I don't know if the same thing would happen on an actual device.

Thanks,
Greg