以编程方式调用 UIRefreshControl 不起作用

Question

我的ViewController 中有一个UIRefreshControl 和一个方法refreshView 来处理“拉动刷新”事件。实际拉动时效果很好，但是当我在代码中调用[refresh beginRefreshing] 时，它只显示刷新动画但不调用refreshView 方法。

这里是viewDidload中初始化刷新控件的代码：

UIRefreshControl *refresh = [[UIRefreshControl alloc] init];
refresh.attributedTitle = [[NSAttributedString alloc] initWithString:@"Pull to Refresh"];
[refresh addTarget:self
            action:@selector(refreshView:)
  forControlEvents:UIControlEventValueChanged];
self.refreshControl = refresh;

Answer 1

根据我对文档的理解：http://developer.apple.com/library/ios/#documentation/uikit/reference/UIRefreshControl_class/Reference/Reference.html

告诉控件刷新操作已启动 以编程方式。 ...当有外部事件时调用此方法 source 触发以编程方式刷新您的表格。

我认为它不是用来启动刷新操作，而只是用于更新它当前正在刷新的刷新控件状态，它会使刷新控件旋转。目的是避免用户拉动表格视图并在它仍在刷新时再次触发刷新操作。

所以你应该自己调用 refreshView: 方法。

Answer 2

只需异步调用 beginRefreshing。

- (void)viewDidLoad {
   [super viewDidLoad];
   // Do any additional setup after loading the view.

   dispatch_async(dispatch_get_main_queue(), ^{
       [refreshControl beginRefreshing];
   });
   //...
}

Answer 3

试试这个

ViewDidLoad

//initialise the refresh controller
refreshControl = [[UIRefreshControl alloc] init];
//set the title for pull request
refreshControl.attributedTitle = [[NSAttributedString alloc]initWithString:@"pull to Refresh"];
//call he refresh function
[refreshControl addTarget:self action:@selector(refreshMyTableView)
         forControlEvents:UIControlEventValueChanged];
self.refreshControl = refreshControl;

方法

-(void)refreshMyTableView{

    //set the title while refreshing
    refreshControl.attributedTitle = [[NSAttributedString alloc]initWithString:@"Refreshing the TableView"];
    //set the date and time of refreshing
    NSDateFormatter *formattedDate = [[NSDateFormatter alloc]init];
    [formattedDate setDateFormat:@"MMM d, h:mm a"];
    NSString *lastupdated = [NSString stringWithFormat:@"Last Updated on %@",[formattedDate stringFromDate:[NSDate date]]];
    refreshControl.attributedTitle = [[NSAttributedString alloc]initWithString:lastupdated];
    //end the refreshing

}

阻止它

[refreshControl endRefreshing];