Caching, styling per window, load on demand, system font support + tests

[mikeger]

Hey
We are having some updates for Classy, based on our most recent usage experience:

• Styling per window
  It might be needed to specify extra windows where Classy should apply the style, or alternatively turn it off for main window.
• Caching
  Our CAS file is taking about 500ms to parse, so we decided to cache it to binary plist using NSCoding, Classy supports now id<CASCacheProtocol> cache property to modify the caching behaviour
• Load on demand
  If app is starting on the background for performing the background tasks (APNS, VoIP, etc) we don't want nether to start Classy, nor to do any activity on views/windows
• System font support
  iOS 9 added SanFrancisco font family, which is hard to mention by name

Also contains tests for some of this functionality. Sorry for such a big PR.

[dnedrow]

@mikeger What was the motivation behind bootStrapClassy? When I moved to v0.2.5 my styling stopped working until I called bootstrapClassy in my app delegate application:didFinishLaunchingWithOptions: method. Is that the correct place to call it?

[dnedrow]

@killobatt Why was this change made, and how should one bootstrap Classy now? IE., what windows are to be provided when calling this?

cc: @mikeger

[mikeger]

@dnedrow it's really nice to hear that someone is using Classy in production!

Sorry for that change sneaking in, since the PR is from master to master it also included all other changes.

bootStrapClassy is useful when

1. Your app sometimes does not need to load classy, for example when the app is started from the push notification on the background.
2. Classy needs to know the full list of windows in the application, if you have more than one.

Real-life use example can be found here: https://github.com/wireapp/wire-ios/blob/75f558d483324946ec846a7b600fef39db8fb09f/Wire-iOS/Sources/AppRootViewController.swift

[dnedrow]

@mikeger cool, thanks. So calling bootstrapClassy as below should be an acceptable setup if there is no need for special window handling?

    [CASStyler bootstrapClassyWithTargetWindows:UIApplication.sharedApplication.windows];

[mikeger]

Yes, if (1) code is not executed in the app extension (then there is no UIApplication) and (2) all your windows are loaded.