当UILabel的文本属性更改时,是否可以设置通知?当我找不到UILabel的UITextFields时,我尝试了一个UITextField,但是它没有起作用.
- [[NSNotificationCenter defaultCenter]
- addObserver:self
- selector:@selector(posttosocial)
- name:UITextFieldTextDidChangeNotification
- object:nowplaying];
解决方法
您可以使用键值观察(KVO):
- [label addObserver:self
- forKeyPath:@"text"
- options:NSKeyValueObservingOptionNew
- | NSKeyValueObservingOptionOld
- context:NULL];
- - (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
- {
- if ([keyPath isEqualToString:@"text"]) {
- /* etc. */
- }
- }