Ios 表单表单viewController（iPad）内的popover中的UIPickerView

我的表单中有一个文本字段。当文本字段被输入时，我希望一个弹出框出现，里面有一个pickerView。我以前使用过popOverController，但在本例中，我不知道如何放置pickerView并将其委托和数据源设置为表单表视图控制器，因为实际上popover需要一个独立的视图控制器

我尝试了以下应用程序：应用程序是通用的，popover没有出现：

- (IBAction)gradeTextfieldPressed:(UITextField *)sender
{

    if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPad) {

        [self.nameTextField resignFirstResponder];
        UIViewController *pickerController = [[UIViewController alloc] init];
        UIPickerView *pickerView = [[UIPickerView alloc] initWithFrame:CGRectMake(self.gradeTextField.center.x, self.gradeTextField.center.y, 320, 320)];
        pickerView.delegate = self;
        pickerView.dataSource = self;
        [pickerController.view addSubview:pickerView];
        UIPopoverController *pickerPopover = [[UIPopoverController alloc] initWithContentViewController:pickerController];
        [pickerPopover presentPopoverFromRect:CGRectMake(self.gradeTextField.center.x, self.gradeTextField.center.y, 320, 320) inView:self.view permittedArrowDirections:UIPopoverArrowDirectionUp animated:YES];
        [self.gradeTextField setInputView:pickerView];
        if ([self.gradeTextField.text isEqualToString:@""]) {
            [self pickerView:pickerView didSelectRow:0 inComponent:0];
        }

    } else if([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone){
        [self.picker setHidden:NO];
        //[self pickerView:self.picker didSelectRow:0 inComponent:0];
        if ([self.gradeTextField.text isEqualToString:@""]) {
            [self pickerView:self.picker didSelectRow:0 inComponent:0];
        }
        [self.gradeTextField setInputView:self.picker];
        [self.nameTextField resignFirstResponder];
        [self.creditstextField resignFirstResponder];
        [self.chaptersTextField resignFirstResponder];
    }    
}

---

其中一种方法是，我发现simple创建一个新的控制器，其中只包含PickerView，在本例中是使用.xib完成的，并且有一个简单的委托协议，让表单表控制器知道何时已拾取了某些内容

@protocol MyPickerDelegate <NSObject>
- (void)valuePicked:(NSString*)value
@end

@interface MyPickerController : UIViewController <UIPickerViewDelegate, UIPickerViewDataSource>
{
    __weak IBOutlet UIPickerView *_pickerView;
}
@property (nonatomic, weak) id<MyPickerDelegate> delegate;

最后，在调用类中，表单表控制器：

- (void)displayPickerFromRect:(CGRect)rect inView:(UIView*)view
{
    if (!_pickerController)
        _pickerController = [[MyPickerController alloc] initWithNibName:nil bundle:nil];

    if (_pickerController)
    {
        _speedPickerController.delegate = self;

        if (!_pickerPopover)
        {
            _pickerPopover = [[UIPopoverController alloc] initWithContentViewController:_pickerController];
            _pickerPopover.popoverContentSize = _pickerController.view.frame.size;
            _pickerPopover.delegate = self;
        }

        [_pickerPopover presentPopoverFromRect:rect inView:self.view permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES];
    }
}

- (void)popoverControllerDidDismissPopover:(UIPopoverController *)popoverController
{
    if (_pickerController)
    {
        _pickerController = nil;
        _pickerPopover = nil;
    }
}

- (void)valuePicked:(NSString*)value
{
   // do something with the picked value
   // dismiss the popover if you want it to go away as soon as a value is picked
}

---

我检查了一下，似乎是谁发的邮件没有找到解决问题的方法：/我发了一些我试过的东西，请看上面，谢谢！

- (void)displayPickerFromRect:(CGRect)rect inView:(UIView*)view
{
    if (!_pickerController)
        _pickerController = [[MyPickerController alloc] initWithNibName:nil bundle:nil];

    if (_pickerController)
    {
        _speedPickerController.delegate = self;

        if (!_pickerPopover)
        {
            _pickerPopover = [[UIPopoverController alloc] initWithContentViewController:_pickerController];
            _pickerPopover.popoverContentSize = _pickerController.view.frame.size;
            _pickerPopover.delegate = self;
        }

        [_pickerPopover presentPopoverFromRect:rect inView:self.view permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES];
    }
}

- (void)popoverControllerDidDismissPopover:(UIPopoverController *)popoverController
{
    if (_pickerController)
    {
        _pickerController = nil;
        _pickerPopover = nil;
    }
}

- (void)valuePicked:(NSString*)value
{
   // do something with the picked value
   // dismiss the popover if you want it to go away as soon as a value is picked
}