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我正在使用带有核心数据的实用程序应用程序模板。在反面视图中，用户可以添加项目，这些项目的品牌和模型在主视图上提供 UIPickerView。

当用户添加项目时，除非她或他关闭应用程序，否则此添加的项目不会出现在选择器行标题中。

如何在不关闭应用程序的情况下加载此标题？谢谢

编辑以添加代码：

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

    //retrieving data from iGear.xcdatamodeld
    iGearAppDelegate *iGearDelegate = [[UIApplication sharedApplication]delegate];
    NSManagedObjectContext *context = [iGearDelegate managedObjectContext];
    NSError *error;

    if (managedObjectContext !=nil) {
        if ([managedObjectContext hasChanges] && [managedObjectContext save:&error]) {
            //NSLog(@"Retrieving: unresolved error %@, %@",error, [error userInfo]);
            abort();
         }
    }

    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc]init];
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Cogset"     inManagedObjectContext:context];

    [fetchRequest setEntity:entity];
    fetchedObjects = [context executeFetchRequest:fetchRequest error:&error];

//#pragma mark UIPickerView

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
    {
        return 1;
    }
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent: (NSInteger)component
 {
    return [fetchedObjects count];
 }

- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
    if (component == 0) 
    {
        cogset = [fetchedObjects objectAtIndex:row];
        return [NSString stringWithFormat:@"%@ %@",cogset.brand,cogset.model];
    }
    return @"";
}

-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
    cassette = [fetchedObjects objectAtIndex:[_chooseCogsetPickerView  selectedRowInComponent:0]];
}
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1 回答 1

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你应该UIPickerViewDelegate为你的 UIPickerView 实现一个。

然后，使用这个委托函数来填充你的选择器视图：

- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component ]
{
 return someValue;
}

如果您发布一些当前正在发生的事情的实际代码，我可以尝试更具体地帮助您。

于 2012-07-10T18:11:25.813 回答