ios - Google Analytics crash with Swift 2.0 -

i've installed googleanalytics cocoapods , tried use it, crashes error:

fatal error: unexpectedly found nil while unwrapping optional value 

the crash occurs in part:

override func viewwillappear(animated: bool) {     super.viewwillappear(animated)      let tracker = gai.sharedinstance().defaulttracker     tracker.set(kgaiscreenname, value: "main")      let builder = gaidictionarybuilder.createscreenview()     tracker.send(builder.build() [nsobject : anyobject]) } 

and when reaching line:

tracker.set(kgaiscreenname, value: "main") 

maybe has framework bridged objective-c?

---

update

so fixed crash wrapping if statment , still nothing sent google analytics:

let name = "main" if let gai = gai.sharedinstance() {     if let tracker: gaitracker = gai.trackerwithtrackingid("tracking_id") {         tracker.set(kgaiscreenname, value: name)          let builder = gaidictionarybuilder.createscreenview()         tracker.send(builder.build() [nsobject : anyobject])          print("tracker initialized")     } } 

the docs gai class have defaulttracker

> convenience, class exposes default tracker instance. initialized nil , set first tracker instantiated in trackerwithtrackingid:. may overridden desired.

so i'm guessing need call trackerwithtrackingid: somewhere, or if doing it, make sure happens before method called.