Question

我尝试将手势识别器添加到特定的tabBar项目的子视图中。我可以成功地将一个添加到tabBar本身，但不是特定的索引。

我能够通过在我的AppDelegate中实现这个来欺骗它基于selectedIndex做出反应：

[self.tabBar.view addGestureRecognizer:longPressNotificationsGR];

-(void)showFilterForNotifications:(UILongPressGestureRecognizer *)gesture {

  if (self.tabBar.selectedIndex == 4) {
      if (gesture.state == UIGestureRecognizerStateBegan) {
          NSLog(@"Began");
      } else if (gesture.state == UIGestureRecognizerStateEnded) {
          NSLog(@"Ended");
      }
  }
}

有更好的方法吗？是的，我知道这不是Apple的想法，但这是我对我的特定项目所需要的。我觉得这不是最好的解决方法，如果有一个，我不确定它在AppDelegate中的性能如何。但最终，我不想这样做，我想将它添加到objectAtIndex:n，这样用户就可以按住tabBar上的任意位置，即使4是当前的选定的指数。现在用户可以点击＆amp;保持索引1图标，如果选择4，则调用手势方法。我希望它只在用户点击时才会发生。坚持objectAtIndex:n

Answer 1

您可以在UITabBar上使用以下类别方法获取特定索引处的选项卡的UIView：

- (UIView*)tabAtIndex:(NSUInteger)index
{
    BOOL validIndex = index < self.items.count;
    NSAssert(validIndex, @"Tab index out of range");
    if (!validIndex) {
        return nil;
    }

    NSMutableArray* tabBarItems = [NSMutableArray arrayWithCapacity:[self.items count]];
    for (UIView* view in self.subviews) {
        if ([view isKindOfClass:NSClassFromString(@"UITabBarButton")] && [view respondsToSelector:@selector(frame)]) {
            // check for the selector -frame to prevent crashes in the very unlikely case that in the future
            // objects that don't implement -frame can be subViews of an UIView
            [tabBarItems addObject:view];
        }
    }
    if ([tabBarItems count] == 0) {
        // no tabBarItems means either no UITabBarButtons were in the subView, or none responded to -frame
        // return CGRectZero to indicate that we couldn't figure out the frame
        return nil;
    }

    // sort by origin.x of the frame because the items are not necessarily in the correct order
    [tabBarItems sortUsingComparator:^NSComparisonResult(UIView* view1, UIView* view2) {
        if (view1.frame.origin.x < view2.frame.origin.x) {
            return NSOrderedAscending;
        }
        if (view1.frame.origin.x > view2.frame.origin.x) {
            return NSOrderedDescending;
        }
        NSLog(@"%@ and %@ share the same origin.x. This should never happen and indicates a substantial change in the framework that renders this method useless.", view1, view2);
        return NSOrderedSame;
    }];

    if (index < [tabBarItems count]) {
        // viewController is in a regular tab
        return tabBarItems[index];
    }
    else {
        // our target viewController is inside the "more" tab
        return [tabBarItems lastObject];
    }
    return nil;
}

然后，您只需要添加手势识别器：

[[self.tabBarController.tabBar tabAtIndex:4] addGestureRecognizer:myGestureRecognizer];

将Gesture Recognizer添加到特定的UITabBarController tabBarItem

1 个答案: