将CoreData对象的字符串属性加载到UIPickerView中 [英] Load CoreData objects' string property into UIPickerView

问题描述

目前我在CoreData应用程式中有一个名为「Events」的实体。 event有一个名为eventName的字符串属性。

在 - （void）viewDidLoad中，我试图获取所有的事件对象并加载他们的eventName 按字母顺序进入UIPickerView。

最终的目标是通过使用一个textField，按钮和pickerView添加新对象并删除不需要的对象。基本上将UIPickerView转换为UITableView。目前我可以将对象保存到CoreData存储，但是无法将它们的属性导出到UIPickerView中。

我愿意并且能够共享

感谢
Chris

div =h2_lin>解决方案

   - （void）update 
 {
 NSMutableArray * array2 = [[NSMutableArray alloc] ; 
 
 CDPickerAppDelegate * appDelegate = [[UIApplication sharedApplication] delegate]; 
 NSManagedObjectContext * moc = [appDelegate managedObjectContext]; 
 NSEntityDescription * entityDescription = [NSEntityDescription entityForName：@EventinManagedObjectContext：moc]; 
 NSFetchRequest * request = [[[NSFetchRequest alloc] init] autorelease]; 
 [request setEntity：entityDescription]; 
 
 NSSortDescriptor * sortDescriptor = [[NSSortDescriptor alloc] initWithKey：@callNameascending：YES]; 
 [request setSortDescriptors：[NSArray arrayWithObject：sortDescriptor]]; 
 [sortDescriptor release]; 
 
 NSArray * array = [moc executeFetchRequest：request error：& error]; 
 
 for（int i = 0; i  Event * theEvent = [array objectAtIndex：i]; 
 
 NSString * StringOne = [NSString stringWithFormat：@％@，theEvent.callName]; 
 
 [array2 addObject：StringOne]; 
 
} 
 
 self.pickerData = array2; 
 [singlePicker reloadAllComponents]; 
 
} 
 
  - （IBAction）addCall {
 CDPickerAppDelegate * appDelegate = [[UIApplication sharedApplication] delegate]; 
 NSManagedObjectContext * context = [appDelegate managedObjectContext]; 
 NSManagedObject * theEvent = [NSEntityDescription insertNewObjectForEntityForName：@EventinManagedObjectContext：context]; 
 
 [theEvent setValue：callField.text forKey：@callName]; 
 
 [context save：& error]; 
 
 callField.text = @; 
 
 [callField resignFirstResponder]; 
 self.update; 
} 
  

Currently I have an entity named "Events" in a CoreData app. "Events" has one string property named "eventName".

In the -(void)viewDidLoad I am trying to Fetch all the "Events" objects and load their "eventName" by alphabetical order into a UIPickerView.

The ultimate end goal is through the use of a textField, buttons and the pickerView being add new objects in and remove unwanted objects out. Basically turning the UIPickerView into a UITableView. Currently I am able to save objects to the CoreData store, but am not able to pull them/their properties out into the UIPickerView.

I am willing and able to share the project source code to anyone who wants it, or is willing to look at it to help out.

thanks Chris

解决方案

-(void)update
{   
    NSMutableArray *array2 = [[NSMutableArray alloc] init];

    CDPickerAppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
    NSManagedObjectContext *moc = [appDelegate managedObjectContext];
    NSEntityDescription *entityDescription = [NSEntityDescription entityForName:@"Event" inManagedObjectContext:moc];
    NSFetchRequest *request = [[[NSFetchRequest alloc] init] autorelease];
    [request setEntity:entityDescription];

    NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"callName" ascending:YES];
    [request setSortDescriptors:[NSArray arrayWithObject:sortDescriptor]];
    [sortDescriptor release];

    NSArray *array = [moc executeFetchRequest:request error:&error];

    for (int i=0; i<array.count; i++) {     
        Event *theEvent = [array objectAtIndex:i];

        NSString *StringOne = [NSString stringWithFormat:@"%@",theEvent.callName];

        [array2 addObject:StringOne];

    }

    self.pickerData = array2;   
    [singlePicker reloadAllComponents];

}

-(IBAction)addCall{
    CDPickerAppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
    NSManagedObjectContext *context = [appDelegate managedObjectContext];   
    NSManagedObject *theEvent = [NSEntityDescription insertNewObjectForEntityForName:@"Event" inManagedObjectContext:context];

    [theEvent setValue:callField.text forKey:@"callName"];

    [context save:&error];

    callField.text=@"";

[callField resignFirstResponder];   
self.update;
}

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