[NSManagedObject isEqualToString:]：无法识别的选择器发送到实例 0x454a590'

Question

我收到上述错误，但不知道它发生在哪里。有什么办法可以调试。我已经设置了一些断点，但它没有改变它没有改变这些区域。

代码如下：

    -(void)viewDidLoad 
    { 
     if (managedObjectContext == nil) 
     { 
            managedObjectContext = [(NewWorkoutViewController *)[[UIApplication sharedApplication] delegate] managedObjectContext]; 
            NSLog(@"After managedObjectContext: %@",  managedObjectContext);
     }

     //Setup PickerView values.  
     [UIView beginAnimations:nil context:nil];
     [UIView setAnimationDuration:1.0];
     CGAffineTransform transform = CGAffineTransformMakeTranslation(0, 480);
     pickerView.transform = transform;
     [UIView commitAnimations];
     // When the view loads, run this action.
     [super viewDidLoad]; // This NEEDS to be here or the application will not work!
     route.delegate = self;

     //Initialise variable.
     counterInt = 0;
    } 


    -(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
    {
     UITouch *touch;
     touch=[touches anyObject];
     CGPoint point=[touch locationInView:self.view];

     if (CGRectContainsPoint([route frame],point))
     {
      [self routePickerShow];
     }

     if (CGRectContainsPoint([activity frame],point))
     {
      [self activityPickerShow];
     }

     if (CGRectContainsPoint([intensity frame],point))
     {
      [self intensityPickerShow];
     }
    }


-(IBAction)routePickerShow
{  
 NSFetchRequest *request = [[NSFetchRequest alloc] init];

 NSEntityDescription *entity = [NSEntityDescription entityForName:@"Route" inManagedObjectContext:managedObjectContext];
 [request setEntity:entity];

 NSError *error = nil;
 NSArray *results = [managedObjectContext executeFetchRequest:request error:&error];

 // Check for errors from the FetchRequest
 if (nil == results || nil != error)
  NSLog(@"Error getting results : %@", error);

 routeArray = [results mutableCopy];
 [request release];

 int arrayItemQuantity = [routeArray count];
 NSLog(@"Array Quantity: %d", arrayItemQuantity);
 int i;

    for (i = 0; i < arrayItemQuantity; i++)
 {  
  NSLog(@"Element %i: %@", i, [[routeArray objectAtIndex:i] valueForKey:@"route_name"]);
  NSLog(@"Element %i: %@", i, [[routeArray objectAtIndex:i] valueForKey:@"route_id"]);
 }

 // Initialise PickerView details.
 [UIView beginAnimations:nil context:nil];
 [UIView setAnimationDuration:0.5];
 CGAffineTransform transform = CGAffineTransformMakeTranslation(0, 200);
 pickerView.transform = transform;
 [self.view addSubview:pickerView];
 [UIView commitAnimations]; 
}


-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)routePicker
{
 return 1;
}


-(NSInteger)pickerView:(UIPickerView *)routePicker numberOfRowsInComponent:(NSInteger)component
{
 return [routeArray count];
}


-(NSString *)pickerView:(UIPickerView *)routePicker titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
 return [routeArray objectAtIndex:row];
}


-(void)pickerView:(UIPickerView *)routePicker didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
 route.text = [[routeArray objectAtIndex:row] valueForKey:@"route_name"];
 mapID = [[routeArray objectAtIndex:row] valueForKey:@"route_id"];
 NSLog(@"Map ID NW: %@", mapID);

 //activity.text = [list objectAtIndex:row];
 //intensity.text = [list objectAtIndex:row];
}

我所知道的是它没有达到方法pickerView，它在此之前异常终止。

Answer 1

您的具体错误是您尝试将字符串设置为 Core Data 对象。 route_id 是对象还是字符串？ mapID 是字符串吗？可能是这一行：

NSLog(@"Element %i: %@", i, [[routeArray objectAtIndex:i] valueForKey:@"route_id"]);

此外，您可能需要添加断点来捕获未捕获的异常。打开断点窗口。选择 Global Breakpoints 组，这样您只需执行一次，它将在所有项目中。将 objc_exception_throw 添加到断点，您将在所有异常崩溃之前捕获所有异常。此外，在您的调试代码中启用 NSZombies。有关一些信息，请参阅 here 和 here。