ios - 分段控件更改时更新 rightBarButtonItems

Question

我想在 segmentedControl 更改时隐藏/显示 UIBarButtonItem，这是我的代码:

@objc fileprivate func handleSegmentedChange() {
        switch segmentedControl.selectedSegmentIndex {
        case index0:
            // Set the proper rightBarButtonItems, in the first load this bar button items will be nil, this is why we have to check first
            self.navigationItem.rightBarButtonItems?.append(UIBarButtonItem(image: #imageLiteral(resourceName: "Filter2"), style: .plain, target: self, action: #selector(openBottomSheet)))

        default:
            self.navigationItem.rightBarButtonItems?.remove(at: 0)
        }
    }

但是不更新 View (隐藏或显示任何内容)。

注意 我也试过在添加或删除项目之前将 rightBarButtonItems 设置为 nil，但是没有用。

我怎样才能达到预期的效果？

Answer 1

如果 rightBarButtonItems 在您尝试向其中添加项目或从中删除项目之前为 nil，则不会发生任何事情，因为您无法向不存在的数组添加项目或从中删除项目。

与其在 rightBarButtonItems 中添加/删除，不如尝试将其直接设置为您想要的项目，如下所示:

@objc fileprivate func handleSegmentedChange() {
    switch segmentedControl.selectedSegmentIndex {
    case 0:
        let barButtonItem = UIBarButtonItem(image: #imageLiteral(resourceName: "Filter2"),
                                            style: .plain,
                                            target: self,
                                            action: #selector(openBottomSheet))
        navigationItem.rightBarButtonItems = [barButtonItem]
        // Note: If you're just dealing with one bar button item, 
        // you could also just use `navigationItem.rightBarButtonItem` like:
        // navigationItem.rightBarButtonItem = barButtonItem

    default:
        navigationItem.rightBarButtonItems = nil // or `= []`
        // Note: If you're just dealing with one bar button item, 
        // you could also just use `navigationItem.rightBarButtonItem` like:
        // navigationItem.rightBarButtonItem = nil
    }
}