addObserver method

void addObserver(
  1. id observer,
  2. Function function,
  3. String name,
  4. id object,
)

Register callback function for notification. The function must have one and only one argument (an instance of NSNotification).

Implementation

void addObserver(id observer, Function function, String name, id object) {
  SEL? selector = _registerNotificationCallback(observer, function);
  if (selector == null) {
    throw 'Selector($selector) already exists when register notification!';
  }
  performSync(SEL('addObserver:selector:name:object:'),
      args: [observer, selector, name, object]);
}