Question

我有一个视图控制器，当用户要求将对象添加到数据库时会触发该控制器。该视图具有文本输入字段以及UIPICKERVIEW。视图加载并正常工作，直到我添加NSMANAGEDOBJECT来存储输入的数据。

标题文件：

    `@property (strong, nonatomic) NSManagedObjectContext *managedObjectContext;`

    `@property (strong, nonatomic) Training *trainingEvent;`
    `@property (retain, nonatomic) NSArray *eventTypes;`

和.m

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

self.typePicker = [[UIPickerView alloc] init];

if (self.managedObjectContext) {
    NSLog(@"managed object context loaded");
} else {
    NSLog(@"no managed object context loaded");
}

NSLog(@"event types loaded :%lu", (long unsigned)self.eventTypes.count);

if (self.trainingEvent) {
    NSLog(@"training event loaded %@", self.trainingEvent.name);
} else {
    //create new event in MOC
    NSLog(@"create new training event");
    NSEntityDescription *trainingEntityDescription = [NSEntityDescription entityForName:@"Training"
                                                                 inManagedObjectContext:self.managedObjectContext];
    Training *newTrainingEvent = (Training *)[[NSManagedObject alloc] initWithEntity:trainingEntityDescription
                                                 insertIntoManagedObjectContext:self.managedObjectContext];
    self.trainingEvent = newTrainingEvent;



}
}

当我注释掉else子句时，（在MOC中创建新事件）视图工作正常。但是如上所述，我收到以下错误：

`*** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArrayI objectAtIndex:]: index 0 beyond bounds for empty array'`

附上UIPICKER方法：

-(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{

//cell.textLabel.text = [arrWebServiceList count] > 0 ? [arrWebServiceList objectAtIndex:indexPath.row] : @"DummyText";
NSLog(@"titleForRow %lu", (long)row);
return [self.eventTypes objectAtIndex:row];
}

-(UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row     forComponent:(NSInteger)component reusingView:(UIView *)view
{
    UILabel *tView = (UILabel *)view;
NSLog(@"viewForRow %lu", (long)row);
if (!tView) {
    tView = [[UILabel alloc] init];


    tView.minimumScaleFactor = 0.5;
    [tView setFont:[UIFont systemFontOfSize:12.0]];
    tView.numberOfLines = 4;
    tView.lineBreakMode = NSLineBreakByWordWrapping;
}

tView.text = [self.eventTypes objectAtIndex:row];


return tView;
}

问题：如何创建核心数据对象来存储数据？

创建Core Data对象时，View Controller崩溃

0 个答案: