Geek asks and answers

A simple setter in objc still generates a value change notification

I have a simple setter like

- (void) setValue: (int) newVal
{
    value = newVal;
}

where valueis the instance variable int value;.

How is it possible that use [myobj setValue: 10];still generates a notification for observers, although my setter does not explicitly notice (i.e., it does not call willChangeValueForKeyand didChangeValueForKey).

Not sure if this is relevant or not, but I'm using the regular old Mac OS X. Is it any different than iOS?

+3
source share
2 answers

Cocoa (and CocoaTouch) use a technique called " isa-swizzling " to automatically support KVO.

, . willChangeValueForKey: didChangeValueForKey: (, , ). ​​

isa ( ) . , , .

+2

:

+ (BOOL)automaticallyNotifiesObserversForKey:(NSString *)theKey

apple KVO , KVO.

+2

More articles:


All Articles