UIRefreshControl是iOS6自帶的UITableView下拉刷新控件。

• (instancetype)init;

@property (nonatomic, readonly, getter=isRefreshing) BOOL refreshing;

@property (null_resettable, nonatomic, strong) UIColor *tintColor;
@property (nullable, nonatomic, strong) NSAttributedString *attributedTitle UI_APPEARANCE_SELECTOR;

// May be used to indicate to the refreshControl that an external event has initiated the refresh action

• (void)beginRefreshing NS_AVAILABLE_IOS(6_0);
  // Must be explicitly called when the refreshing has completed
• (void)endRefreshing NS_AVAILABLE_IOS(6_0);

// UITableView
_tableView = [[UITableView alloc] initWithFrame:self.view.frame style:UITableViewStylePlain];
_tableView.delegate = self;
_tableView.dataSource = self;
[_tableView registerClass:[UITableViewCell class] forCellReuseIdentifier:@"UITableViewCell"];
[self.view addSubview:_tableView];

// UIRefreshControl  
_refreshControl = [[UIRefreshControl alloc] init];  
_refreshControl.tintColor = [UIColor redColor];  
_refreshControl.attributedTitle = [[NSAttributedString alloc] initWithString:@"下拉刷新"];  
[_refreshControl addTarget:self action:@selector(refreshControlAction) forControlEvents:UIControlEventValueChanged];  
[_tableView addSubview:_refreshControl];