NSInvocation & NSTimeR语言 方法被调用两次

Question

我创建了一个小应用程序，它有一个UISegmentedControl和一个UITableView。当选定的段发生更改时，TableView（从服务器下载）中的数据应该会发生更改。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是用于获取正确数据的索引。前两行获取tableView的数据。

每次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];
   }
}

这是我的视图DidLoad

- (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];
}

所以现在我的问题是：每次定时器用完并再次调用该方法时，我的viewDidLoad的两条语句都会被调用（我已经用NSLog语句检查过了）。因此，在应用程序中显示索引1的数据，然后才显示正确的数据（索引0）

我该怎么解决这个问题？

Answer 1

您应该将调度逻辑从loadPlanForIndex:方法中移出

- (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];
}

注意到NSTimer现在是repeats。我不能运行这个，但我认为它应该有效。无论如何，您可能希望将计时器保存在一个变量中，以便在viewDidDisappear或类似的程序中停止它。