You have too many protocols in your URL. Get rid of https: so the URL reads
https:
itms-apps://itunes.apple.com/app/bars/id706081574
Just by following older answers I couldn't make it work, so here I post my complete solution:
if let url = NSURL(string: "itms-apps://itunes.apple.com/app/id1234567890"), UIApplication.shared.canOpenURL(url) { UIApplication.shared.openURL(url) }}
Use just the short "itms://".
For Swift 3 this is the snippet:
UIApplication.shared.openURL(URL(string: "itms://itunes.apple.com/app/id" + appStoreAppID)!)
I hope this helps someone.
Cheers.
P.S. @Eric Aya was ahead of the time :)