重新加载UINavigationItem

Question

我希望用一个navItem.rightBarButtonItem加载我的视图控制器，并根据一组情况将它更改为另一个。似乎我只能在viewDidLoad上加载一次。在更改图标后，是否有更新bar按钮项的方法？

func viewDidLoad() {
    var iconOne = UIImage(named: "button")
    let buttonOne = UIBarButtonItem(image: iconOne, style: UIBarButtonItemStyle.Plain, target: self, action: "funcOne")
    self.navItem.rightBarButtonItem = buttonOne

    //perform async query, if a condition holds true then:

    var iconTwo = UIImage(named: "buttonTwo")
    let buttonTwo = UIBarButtonItem(image: iconTwo, style: UIBarButtonItemStyle.Plain, target: self, action: "funcTwo")
    self.navItem.rightBarButtonItem = buttonTwo
}

完整代码：

override func viewDidLoad() {
        super.viewDidLoad()


        // Sets custom nav bar view so we can add multiple bar buttons
        navBar = UINavigationBar(frame: CGRectMake(0, 20, UIScreen.mainScreen().bounds.size.width, 44))
        navBar.barTintColor = UIColor.blackColor() // Sets bar to black
        navBar.translucent = false
        self.view.addSubview(navBar)
        navItem = UINavigationItem(title: "\(name)") // Sets title
        navBar.titleTextAttributes = [ NSFontAttributeName: UIFont(name: "Helvetica Neue", size: 25)!,  NSForegroundColorAttributeName: UIColor.whiteColor()]
// Set icons
            var backIcon = UIImage(named: "backButton")
            let backButton = UIBarButtonItem(image: backIcon, style: UIBarButtonItemStyle.Plain, target: self, action: "backButton")
            navItem.leftBarButtonItem = backButton

            var userQuery = PFQuery(className: "Followers")
            userQuery.whereKey("following", equalTo: username)
            userQuery.findObjectsInBackgroundWithBlock({ (objects, error) -> Void in
                if error == nil {

                    if let objects = objects {

                        for object in objects {

                            if let follower = object["follower"] as? String {
                                if follower == PFUser.currentUser()!.username! {
                                    var followingIcon = UIImage(named: "followingButton")
                                    let followingButton = UIBarButtonItem(image: followingIcon, style: UIBarButtonItemStyle.Plain, target: self, action: "unfollowUser")
                                    self.navItem.rightBarButtonItem = followingButton

                                    self.navItem.rightBarButtonItem?.tintColor = UIColor.orangeColor()
                                } else {

                                    var followIcon = UIImage(named: "followButton")
                                    let followButton = UIBarButtonItem(image: followIcon, style: UIBarButtonItemStyle.Plain, target: self, action: "followUser")
                                    self.navItem.rightBarButtonItem = followButton


                                    self.navItem.rightBarButtonItem?.tintColor = UIColor.darkGrayColor()
                                }
                            }
                        }

                    }
                } else {
                    println(error)
                }
            })

Answer 1

我不确定这是否可能。因此，我创建了自己的自定义视图，每个条形按钮项目都在那里。我在var rightButton = UIButton(frame: CGRectMake(UIScreen.mainScreen().bounds.width - 50, 25, 30, 30))设置了右边的bar按钮项，添加了一个操作，并将子视图添加到视图中。