Objective-C 觀察者模式--KVO和NSNotificationCenter的使用

標籤：load   after   new   修改   通知   model   move   key   修改屬性   

Objective-C中的KVO和NSNotificationCenter的原理是觀察模式的很好實現, 下面用代碼分別示範下用法

 

KVO的用法

 1 - (void)viewDidLoad { 2     [super viewDidLoad]; 3     // Do any additional setup after loading the view, typically from a nib. 4  5     self.model = [Model new]; 6      7     //添加KVO 8     [self.model addObserver:self 9                  forKeyPath:@"name"10                     options:NSKeyValueObservingOptionNew11                     context:nil];12     13     //發送資訊, 通過修改屬性14     self.model.name = @"v1.0";15      16 }17 18 #pragma mark - KVO方法19 - (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSKeyValueChangeKey,id> *)change context:(void *)context {20     NSLog(@"%@", change);21 }22 23 - (void)dealloc {24 25     //移除KVO26     [self.model removeObserver:self27                     forKeyPath:@"name"];28 }

 

 

NSNotificationCenter的用法

 1 - (void)viewDidLoad { 2     [super viewDidLoad]; 3     // Do any additional setup after loading the view, typically from a nib. 4      5     //添加 6     [[NSNotificationCenter defaultCenter] addObserver:self 7                                              selector:@selector(notificationCenterEvent:) 8                                                  name:@"SCIENCE" 9                                                object:nil];10     11     //發送資訊12     [[NSNotificationCenter defaultCenter] postNotificationName:@"SCIENCE"13                                                         object:@"v1.0"];14     15 }16 17 #pragma mark - 通知中樞方法18 - (void)notificationCenterEvent:(id)sender {19     NSLog(@"%@", sender);20 }21 22 - (void)dealloc {23     //移除通知中樞24     [[NSNotificationCenter defaultCenter] removeObserver:self25                                               forKeyPath:@"SCIENCE"];26 27 }

 

Objective-C 觀察者模式--KVO和NSNotificationCenter的使用