使用UIRefreshControl

Question

目前,我有一个正在使用的应用程序UIRefreshControl.

我有一些问题但是......

继承我的代码:

- (void)viewDidLoad
{
    [super viewDidLoad];
    self.searchDisplayController.delegate = self;
    UIRefreshControl *refreshControl = [[UIRefreshControl alloc] init];
    [refreshControl addTarget:self action:@selector(refresh:) forControlEvents:UIControlEventValueChanged];
    [self.rearTableView addSubview:refreshControl];
}


- (void)refresh:(UIRefreshControl *)refreshControl {
    [refreshControl beginRefreshing];
    [NSTimer scheduledTimerWithTimeInterval:2.0 target:self selector:@selector(endRefresh:) userInfo:nil repeats:NO];
}

- (void)endRefresh:(UIRefreshControl *)refresh
{
    [refresh endRefreshing];
}

拉取tableview会初始化timer但是2秒数已经上升...我的应用程序crashes并发送此消息:

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFTimer endRefreshing]: unrecognized selector sent to instance 0x9c093c0'

我很迷惑 :(

Answer 1

问题:

出现此问题是因为:

[NSTimer scheduledTimerWithTimeInterval:2.0 target:self selector:@selector(endRefresh:) userInfo:nil repeats:NO];

您将添加endRefresh:为计时器的选择器.所以endRefresh:方法的参数NSTimer不是UIRefreshControl.

实际的方法签名如下所示:

- (void)endRefresh:(NSTimer *)refresh
{
   //your code
}

您正在调用该endRefreshing NSTimer对象,这就是崩溃发生的原因.

声明如下:

- (void)endRefresh:(UIRefreshControl *)refresh

只是强制攻击NSTimer对象UIRefreshControl.

它相当于:

- (void)endRefresh:(NSTimer *)timer
{
   UIRefreshControl *refresh = (UIRefreshControl *)timer;
   [refresh endRefreshing];
}

解决方案1:

声明UIRefreshControl为属性并使用它.

解决方案2:

改变你的方法,如:

- (void)refresh:(UIRefreshControl *)refreshControl
{
    [refreshControl beginRefreshing];
    [self performSelector:@selector(endRefresh:) withObject:refreshControl afterDelay:2.0f];
}

- (void)endRefresh:(UIRefreshControl *)refresh
{
    [refresh performSelectorOnMainThread:@selector(endRefreshing) withObject:nil waitUntilDone:NO];
}