自定义UIStoryboardPopoverSegue无法在iOS 5.1下运行

Question

我已经实现了一个自定义的故事板segue，它在iOS 6下工作正常但在iOS 5.1下的模拟器中没有任何反应。 问题是popoverController在iOS 5.1下总是为零？

@implementation PopoverFromRectSegue  

-(id)initWithIdentifier:(NSString *)identifier
             source:(UIViewController *)source
        destination:(UIViewController *)destination {

  if(self = [super initWithIdentifier:identifier
                             source:source
                        destination:destination]) {
  }

  return self;
}

- (void)perform {
    UIPopoverController *popCtrl = ((UIStoryboardPopoverSegue *)self).popoverController;

    id controller = [self sourceViewController];
    if ([controller isKindOfClass:[UIViewController class]] && [controller respondsToSelector:@selector(popoverRect)]) {
    [popCtrl presentPopoverFromRect:[[controller performSelector:@selector(popoverRect)] CGRectValue] inView:[controller view] permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES];
  }
}
@end

感谢任何帮助/提示。

编辑： 刚刚制作了新的样本项目。似乎在iOS5.1下没有设置popoverController 用于自定义UIStoryBoardSegues。 我还可以做些什么。 普通的popover需要一个锚，但不接受原型tableView单元格（编译时失败），我找不到修改弹出窗口的矩形的方法。

Answer 1

这是我的解决方法 的 PopoverFromRectSegue.h

@interface PopoverFromRectSegue : UIStoryboardPopoverSegue
  @property (strong, nonatomic) UIPopoverController *popoverCtrl;
@end

PopoverRectFromSegue.m

#import "PopoverFromRectSegue.h"
@implementation PopoverFromRectSegue

- (void)perform
{
  UIPopoverController *popCtrl = ((UIStoryboardPopoverSegue *)self).popoverController;

  // under iOS 5.1 the popoverController iVar is not set
  // so we have to use our own one
  if (nil == popCtrl) {
    popCtrl = self.popoverCtrl;
  }

  id controller = [self sourceViewController];
  if ([controller isKindOfClass:[UIViewController class]] && [controller respondsToSelector:@selector(popoverRect)]) {
    [popCtrl presentPopoverFromRect:[[controller performSelector:@selector(popoverRect)] CGRectValue] inView:[controller view] permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES];
  }
}

@end

在我的prepareForSegue方法中，我执行以下操作。

    if (isPad) {
      self.popoverCtrl = [(UIStoryboardPopoverSegue *)segue popoverController];
      if (nil == _popoverCtrl) {
        self.popoverCtrl = [[UIPopoverController alloc] initWithContentViewController:[segue destinationViewController]];
        ((PopoverFromRectSegue *)segue).popoverCtrl = _popoverCtrl;
      }
      self.popoverRect = [NSValue valueWithCGRect:[self.myTableView rectForRowAtIndexPath:indexPath]];
  }