Objective-C property change macro for better KVO using willChangeValueForKey/didChangeValueForKey

objcpropertychangemacro.m

// Note: This requires libextobjc: https://github.com/jspahrsummers/libextobjc

inline static void propertyChangeObject(NSObject *object, NSString *keypath, void (^block)()) {
    [object willChangeValueForKey: keypath];
    block();
    [object didChangeValueForKey: keypath];
}

#define propertyChange(__KEY, block) propertyChangeObject(self, @keypath(self.__KEY), block)
#define propertyChange2(keypath, block) propertyChangeObject(self, keypath, block)

// Examples:
propertyChange(propertyName, ^{
    // propertyName is checked at compile-time for object self
});

propertyChange2(@keypath(self.propertyName), ^{
    // propertyName is checked at compile-time for the given keypath using @keypath macro
});

propertyChange2(@"propertyName", ^{
    // WARNING: This works too...but propertyName is not checked to belong to self.
});

// The first two examples above are better than the following:
[self willChangeValueForKey: @"propertyName"];
// Do something...
[self didChangeValueForKey: @"propertyName"];