NSSlider如何实时更新价值？

- (IBAction)sliderValueChanged:(NSSlider *)sender {
    NSLog(@"Slider value: %f", sender.floatValue);
}

Bind to: model
Controller Key: sliderValue
Model Key Path: sliderValue

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSKeyValueChangeKey,id> *)change context:(void *)context {
    if ([keyPath isEqualToString:@"sliderValue"]) {
        NSLog(@"Slider value: %f", [change[NSKeyValueChangeNewKey] floatValue]);
    }
}

- (void)slider:(NSSlider *)slider didChangeValue:(float)newValue {
    NSLog(@"Slider value: %f", newValue);
}