Question

我已经创建了一个小应用程序，它有一个带有段和UITableView的UISegmentedControl。当选定的段更改时，TableView中的数据（从服务器下载）应该更改。因此我有一个方法

- (void)loadPlanForIndex:(int)tableIndex
{
   // Create PlanModel and get elements
   _planModel =[[PlanModel alloc] init];
   _plan = [_planModel getPlanForDayIndex:tableIndex];

   // Reload TableView data
   [self.firstTable reloadData];

   // Set SegmentedControl title
   NSString *segmentTitle = @„MyTitle“;
   [self.daySegmentedControl setTitle:segmentTitle forSegmentAtIndex:tableIndex];

   // Create NSInvocation to call method with parameters
   NSInteger objIndex = tableIndex;
   SEL selector = @selector(loadPlanForIndex:);
   NSMethodSignature *signature = [self methodSignatureForSelector:selector];
   NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:signature];
   [invocation setTarget:self];
   [invocation setSelector:selector];
   [invocation setArgument:&objIndex atIndex:2];

   NSTimeInterval timeInterval = 10;
   [NSTimer scheduledTimerWithTimeInterval:timeInterval invocation:invocation repeats:NO];
}

tableIndex是获取正确数据的索引。前两行获取tableView的数据。

每次分段更改时都会调用此方法

- (IBAction)didSelectSegment:(id)sender
{
   if (self.daySegmentedControl.selectedSegmentIndex == 0)
   {
       [self loadPlanForIndex:0];
   }

   else
   {
       [self loadPlanForIndex:1];
   }
}

这是我的viewDidLoad

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

   // Some other setup

   [self loadPlanForIndex:1];
   [self loadPlanForIndex:0];
}

所以现在这是我的问题：每次计时器用完并再次调用该方法时，我的viewDidLoad的两个语句被调用（我已经用NSLog语句检查了它）。因此，在应用程序中，将显示索引1的数据，并且仅在此之后显示正确的数据（对于索引0）

我该如何解决这个问题？

Answer 1

您应该将调度逻辑移出loadPlanForIndex:方法

- (void)loadPlanForIndex:(int)tableIndex
{
   // Create PlanModel and get elements
   _planModel =[[PlanModel alloc] init];
   _plan = [_planModel getPlanForDayIndex:tableIndex];

   // Reload TableView data
   [self.firstTable reloadData];

- (void) scheduleAutoReload
   // Set SegmentedControl title
   NSString *segmentTitle = @„MyTitle“;
   [self.daySegmentedControl setTitle:segmentTitle forSegmentAtIndex:tableIndex];

   // Create NSInvocation to call method with parameters
   NSInteger objIndex = tableIndex;
   SEL selector = @selector(loadPlanForIndex:);
   NSMethodSignature *signature = [self methodSignatureForSelector:selector];
   NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:signature];
   [invocation setTarget:self];
   [invocation setSelector:selector];
   [invocation setArgument:&objIndex atIndex:2];

   NSTimeInterval timeInterval = 10;
   [NSTimer scheduledTimerWithTimeInterval:timeInterval invocation:invocation repeats:YES];
}

- (void)viewDidLoad
{
   [super viewDidLoad];
   [self loadPlanForIndex:1];
   [self scheduleAutoReload];
}

注意NSTimer现在是repeats。我不能运行这个，但我认为它应该工作。无论如何，您可能希望将该计时器保留在变量中，以便可以在viewDidDisappear或类似的内容中将其停止。

NSInvocation＆amp; NSTimer - 方法被调用两次

1 个答案: