使用KVO在UITableView中重新加载数据

#define KVO_KEY_FOR_TABLE_VIEW            @"tableView"
#define KVO_KEY_FOR_TABLE_VIEW_NUMBER_OF_SECTIONS @"numberOfSections"
#define KVO_KEY_FOR_TABLE_VIEW_NUMBER_OF_ROWS_IN_SECTION @"numberOfRowsInSection"

- (void)viewDidLoad {
    [super viewDidLoad];
    
    // Add KVO observers
    [self addObserver:self forKeyPath:KVO_KEY_FOR_TABLE_VIEW options:NSKeyValueObservingOptionNew context:nil];
    [self addObserver:self forKeyPath:KVO_KEY_FOR_TABLE_VIEW_NUMBER_OF_SECTIONS options:NSKeyValueObservingOptionNew context:nil];
    [self addObserver:self forKeyPath:KVO_KEY_FOR_TABLE_VIEW_NUMBER_OF_ROWS_IN_SECTION options:NSKeyValueObservingOptionNew context:nil];
}

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
    if ([keyPath isEqualToString:KVO_KEY_FOR_TABLE_VIEW_NUMBER_OF_SECTIONS]) {
        // The number of sections has changed, reload the table view
        [self.tableView reloadData];
    } else if ([keyPath isEqualToString:KVO_KEY_FOR_TABLE_VIEW_NUMBER_OF_ROWS_IN_SECTION]) {
        // The number of rows in a section has changed, reload the relevant rows
        NSInteger section = [change[NSKeyValueChangeNewKey] integerValue];
        NSInteger numberOfRows = [self.tableView numberOfRowsInSection:section];
        [self.tableView reloadRowsAtIndexPaths:[NSIndexPath indexPathsForRowsInSection:section] withRowAnimation:UITableViewRowAnimationAutomatic];
    }
}

- (void)dealloc {
    // Remove KVO observers
    [self removeObserver:self forKeyPath:KVO_KEY_FOR_TABLE_VIEW];
    [self removeObserver:self forKeyPath:KVO_KEY_FOR_TABLE_VIEW_NUMBER_OF_SECTIONS];
    [self removeObserver:self forKeyPath:KVO_KEY_FOR_TABLE_VIEW_NUMBER_OF_ROWS_IN_SECTION];
}