ios - 如何更改 "back"栏按钮项的标题？

Question

我想将“Root View Controller”后退按钮更改为“Back”而不更改 Root View Controller 的标题。

我已经尝试了这 3 个代码，但它们都不起作用。

navigationItem.backBarButtonItem?.title = "Back"
navigationItem.leftBarButtonItem?.title = "Back"
navigationItem.backBarButtonItem?.title = "Back"

我可以知道我做错了什么吗？提前致谢。

下面是整个方法的代码，供大家引用:

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    navigationItem.backBarButtonItem?.title = "Back"
    navigationItem.leftBarButtonItem?.title = "Back"

    manager = CLLocationManager()
    manager.delegate = self
    manager.desiredAccuracy = kCLLocationAccuracyBest

    if activePlace == -1
    {
        manager.requestWhenInUseAuthorization()
        manager.startUpdatingLocation()
    }
    else
    {
       // print( "String(myvar3.dynamicType) -> \(places[activePlace]["lat"].dynamicType)")
        let latitude = Double(places[activePlace]["lat"]!)
        let longitude = Double(places[activePlace]["lon"]!)

        //creating map region and annotation
        createMapRegionAndAnnotation(latitude!, longitude: longitude!)

        print(latitude)
    }

Answer 1

尝试覆盖之前的屏幕转场

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    let backItem = UIBarButtonItem()
    backItem.title = "My title"
    navigationItem.backBarButtonItem = backItem
}