Question

我试图消除PickerView的一个烦人的事情是，如果用户必须从零行移开并再次重新选择它。我希望如果用户决定选择零行，他只需按下按钮即可转到下一个视图，并选择行零值。

任何想法？

非常感谢

这是我的代码 - 目前，如果按下连接到saveSelectedCondition的按钮，并且pickerView没有从第0行移开，则为selectedCondition返回null，而不是第0行的条件值：

   - (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component {

        Condition *condition = [[self.fetchedResultsController fetchedObjects] objectAtIndex:row];
        self.selectedCondition = condition;
        NSLog(@"The '%@' condition was selected using the picker", self.selectedCondition.name);
    }

    - (IBAction)saveSelectedCondition:(id)sender {
        [self.selectedCondition setValue:@"YES" forKey:@"isSelectedCondition"];
        [self.managedObjectContext save:nil];
        NSLog(@"Saving selected condition (%@) with isSelectedCondition set to '%@'", self.selectedCondition.name, self.selectedCondition.isSelectedCondition);
    }

Answer 1

试试吧......

- (IBAction)saveSelectedCondition:(id)sender {
    myText.text = [myArray objectAtIndex:0];//Just add this line for set first value
    [self.selectedCondition setValue:@"YES" forKey:@"isSelectedCondition"];
    [self.managedObjectContext save:nil];
    NSLog(@"Saving selected condition (%@) with isSelectedCondition set to '%@'", self.selectedCondition.name, self.selectedCondition.isSelectedCondition);
}

Set first value when your picker view called.

Answer 2

我现在使用以下代码在performFetch之后将其整理出来：

 [self performFetch];
    NSLog(@"The following Conditions were fetched for the Picker by SelectorViewController:");
    for (Condition *fetchedCondition in [self.fetchedResultsController fetchedObjects]) {
        if (fetchedCondition ==[[self.fetchedResultsController fetchedObjects] objectAtIndex:0])
        {[fetchedCondition setValue:@"YES" forKey:@"isSelectedCondition"];
            self.selectedCondition = fetchedCondition;}
        else
        [fetchedCondition setValue:@"NO" forKey:@"isSelectedCondition"];    
        [self.managedObjectContext save:nil];
        NSLog(@"Condition: %@, isSelectedCondition %@", fetchedCondition.name, fetchedCondition.isSelectedCondition);
    }

}

如果没有触及PickerView，UIPickerView会选择第零行

2 个答案: