Upgrading Swift Projects from Xcode 6 to Xcode 7

With the official release of Xcode 7 and Swift 2 along with iOS9 last week comes the process of needing to upgrade Xcode 6 projects to Xcode 7, but more importantly, changes in the Swift language.

One of the biggest changes in Swift is the new approach to error handling. Take for instance setting up a shared audio session for backgrounding. Before we would have simply typed

AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback, error: nil)

and could ignore any errors, but now we are forced to deal with them

do {
  try AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback)
} catch {
  print( "There was an error \(error)" )
}

Although it might seem like a pain typing this extra code, it is clearly much safer and should help debugging.

Another change is that certain NSString methods are no longer automatically bridged to String it seems, for instance stringByDeletingPathExtension returns an error that NSURL should be used instead. Although Apple has been directing developers to embrace NSURL over strings for dealing with paths, the truth is that some major method calls like

NSBundle.mainBundle().pathForResource()

and

NSFileManager.defaultManager().fileExistsAtPath()

still require paths as strings. These NSString functions can be manually extended to String

extension String
{
  var stringByDeletingPathExtension: String {
    get { return (self as NSString).stringByDeletingPathExtension }
}

Another major change is that of App Transport Security which, although makes complete sense to implement, seems to have a bug for certain HTTPS domains and so (in the case of download from Soundcloud), this needs to be disabled by adding the following entry to info.plist

<key>NSTransportSecurity</key>
  <dict>
    <key>NSAllowsArbitraryLoads</key><true />
  </dict>

Otherwise println has been replaced by print and some ! and ? will have changed due to changes in casting. BTW if you wish to get hands-on with tvOS, you need to download the newest Xcode beta. This also included iOS 9.1.