Question

我想从我的Main.xcdatamodeld（coredata）中的“table”中检索一个类型列表，以放入UIPickerView。此实体“类型”只有一个属性“名称”（字符串）。

如果我在NSMutableArray中添加一些字符串，它就可以完美地运行。 UIPickerView显示字符串。上面是简单的NSMutableArray。

resultFetch = [[NSMutableArray alloc]initWithObjects:@"Electronics",@"School",@"Kitchen",@"Office", nil];

但是当我从coredata中取出时，我得到一个错误。这是下面的代码。

AddItemViewController.m

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

nameField.text = [self.currentItem name];
locationField.text = [self.currentItem location];
//typeField.text = [self.currentItem type];
quantityField.text = [[self.currentItem quantity] stringValue];

self.nameField.delegate = self;
self.locationField.delegate = self;
//self.typeField.delegate = self;
self.quantityField.delegate = self;
NSLog(@"ViewDidload before put fetch in array");
//Put fetch in NSArray resultFetch

AppDelegate *myApp = (AppDelegate *) [[UIApplication sharedApplication]delegate];

resultFetch = [[NSMutableArray alloc] init];
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Type" inManagedObjectContext:[myApp managedObjectContext]];
[fetchRequest setEntity:entity];

NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
[fetchRequest setSortDescriptors:sortDescriptors];

NSError *error;
NSArray *fetchedObjects = [[myApp managedObjectContext] executeFetchRequest:fetchRequest error:&error];

for (Type *t in fetchedObjects) {

    [resultFetch addObject:t];
    NSLog(@"resultFetch: %@", resultFetch);

}

//Define typePicker
typePicker = [[UIPickerView alloc] initWithFrame:CGRectMake(0,43,320,480)];
typePicker.delegate = self;
typePicker.dataSource = self;
[typePicker setShowsSelectionIndicator:YES];
typeField.inputView = typePicker;

//Create done button in UIPickerView
myPickerToolbar = [[UIToolbar alloc] initWithFrame:CGRectMake(0, 0, 320, 56)];
myPickerToolbar.barStyle = UIBarStyleBlackOpaque;
[myPickerToolbar sizeToFit];

NSMutableArray *barItems = [[NSMutableArray alloc] init];
UIBarButtonItem *flexSpace = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:self action:nil];
[barItems addObject:flexSpace];

UIBarButtonItem *doneBtn = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:@selector(pickerDoneClicked)];
[barItems addObject:doneBtn];
[myPickerToolbar setItems:barItems animated:YES];
typeField.inputAccessoryView = myPickerToolbar;
 NSLog(@"End ViewDidLoad");

}

-(void)pickerDoneClicked
{
NSLog(@"Done Clicked");

[typeField resignFirstResponder];
myPickerToolbar.hidden=YES;
typePicker.hidden=YES;
}

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

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

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

- (void) pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
typeField.text = [resultFetch objectAtIndex:row];
}

错误是：

2013-11-14 10：31：53.099存储[1226：70b]在数据库中提取之前的ViewDidload

2013-11-14 10：31：53.102存储[1226：70b] resultFetch :( “（entity：Type; id：0x8a83e50; data：）” ）

2013-11-14 10：31：53.103存储[1226：70b] resultFetch :( “（entity：Type; id：0x8a83e50; data：）”， “（entity：Type; id：0x8a6ae80; data :)）” ）

2013-11-14 10：31：53.104存储[1226：70b] resultFetch :( “（entity：Type; id：0x8a83e50; data：）”， “（entity：Type; id：0x8a6ae80; data :)）， “（entity：Type; id：0x8aa9650; data：）” ）

2013-11-14 10：31：53.107存储[1226：70b]结束ViewDidLoad

2013-11-14 10：31：57.148存储[1226：70b] - [类型长度]：无法识别的选择器发送到实例0x8aa08e0

它不显示数据库中的类型名称。你能帮我正确地获取这个“表”来将这些属性字符串放在UIPickerView中吗？我想要的只是一个可以使用的漂亮的NSMutableArray！：）

非常感谢你的帮助。

保

Answer 1

问题解决了！从[resultFetch addObject：t]更改了for语句中的行;到[resultFetch addObject：t.name] ;. 好像垃圾太多了！ :)

从核心数据表中检索数据到UIPickerView（在文本字段内）

1 个答案: