爲什麼不看按鈕？

Question

任務是選擇文本字段的日期。開發是在iPad上，所以我使用UIPopover。但是我需要兩個按鈕。我正在嘗試這樣做，但不顯示按鈕。可能是什麼問題？

請看截圖：

而且全碼：

dateSheet = [[UIActionSheet alloc] initWithTitle:nil delegate:nil cancelButtonTitle:nil destructiveButtonTitle:nil otherButtonTitles:nil]; 
[dateSheet setActionSheetStyle:UIActionSheetStyleBlackTranslucent]; 

CGRect pickerFrame = CGRectMake(0, 44, 0, 0); 
UIDatePicker *dayPicker = [[UIDatePicker alloc] initWithFrame:pickerFrame]; 
[dayPicker setDatePickerMode:UIDatePickerModeDate]; 
[dateSheet addSubview:dayPicker]; 
[dayPicker release]; 

UIToolbar *controlToolBar = [[UIToolbar alloc] initWithFrame:CGRectMake(0, 0, dateSheet.bounds.size.width, 44)]; 
[controlToolBar setBarStyle:UIBarStyleBlackTranslucent]; 
[controlToolBar sizeToFit]; 

UIBarButtonItem *spacer = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil]; 
UIBarButtonItem *setButton; 
setButton = [[UIBarButtonItem alloc] initWithTitle:@"Установить" style:UIBarButtonItemStyleDone target:self action:@selector(dismissDateStart:)]; 
setButton.tag = pTag; 
UIBarButtonItem *cancelButton = [[UIBarButtonItem alloc] initWithTitle:@"Отменить" style:UIBarButtonItemStyleBordered target:self action:@selector(cancelDateStart)]; 
[controlToolBar setItems:[NSArray arrayWithObjects:spacer, cancelButton, setButton, nil] animated:NO]; 
[spacer release]; 
[setButton release]; 
[cancelButton release]; 



UIViewController* popoverContent = [[UIViewController alloc] init]; 
UIView* popoverView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, 344)]; 
popoverView.backgroundColor = [UIColor whiteColor]; 

dateSheet.frame = CGRectMake(0, 0, 320, 344); 

[popoverView addSubview:dateSheet]; 
[popoverView addSubview:controlToolBar]; 
popoverContent.view = popoverView; 

popoverContent.contentSizeForViewInPopover = CGSizeMake(320, 244); 

popoverController = [[UIPopoverController alloc] initWithContentViewController:popoverContent]; 

[popoverController presentPopoverFromRect:changeDateStartField.frame inView:self.view permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES]; 
[popoverView release]; 
[popoverContent release]; 

Answer 1

，則應該更換

UIBarButtonSystemItemFlexibleSpace 

到

UIBarButtonSystemItemFixedSpace 

你的間隔按鈕