Carthage support

[eunikolsky]

Here's a new dependency manager for Cocoa: https://github.com/Carthage/Carthage, which is not a replacement for CocoaPods. We should check if ConnectSDK is built fine and can be used from Carthage. And publish a config file for the project if necessary.

[eunikolsky]

0 Carthage requires a shared dynamic framework scheme in the project (created here: https://github.com/eunikolsky/Connect-SDK-iOS/tree/feature/carthage_support).

1 The built dynamic framework should be embedded into the app in project's target settings => General => Embedded Binaries section.

Issues so far:

0 Build warnings like:

/Users/q/proj/csdk-sampler-carthage/ConnectSDKSampler/ControlFlow/SamplerViewController.m:18:2: warning: missing submodule 'ConnectSDK.AirPlayService' [-Wincomplete-umbrella]
#import <ConnectSDK/AirPlayService.h>
 ^      ~
In file included from /Users/q/proj/csdk-sampler-carthage/ConnectSDKSampler/ControlFlow/SamplerViewController.m:18:
/Users/q/proj/csdk-sampler-carthage/Carthage/Build/iOS/ConnectSDK.framework/Headers/AirPlayService.h:25:2: warning: missing submodule 'ConnectSDK.AirPlayServiceHTTP' [-Wincomplete-umbrella]
#import "AirPlayServiceHTTP.h"
 ^      ~~~~~~~~~~~~~~~~~~~~~~

and

<module-includes>:1:1: warning: umbrella header for module 'ConnectSDK' does not include header 'AirPlayService.h' [-Wincomplete-umbrella]
#import "/Users/q/proj/csdk-sampler-carthage/Carthage/Build/iOS/ConnectSDK.framework/Headers/ConnectSDK.h"
^
<module-includes>:1:1: warning: umbrella header for module 'ConnectSDK' does not include header 'AirPlayServiceHTTP.h' [-Wincomplete-umbrella]
<module-includes>:1:1: warning: umbrella header for module 'ConnectSDK' does not include header 'AirPlayServiceHTTPKeepAlive.h' [-Wincomplete-umbrella]

1 Cast and FireTV devices are not discovered (after manually linking them with the app (there was no warning that they were required (which is another issue))).

[eunikolsky]

Re 1: I forgot to include those classes in the framework — fixed now. However, the user should now build the framework differently:

carthage update
rsync frameworks
carthage build

You still don't get linker errors if you don't link those frameworks with the app — the app crashes at runtime. I suppose, we could link them weakly, that would require extra checks.

[eunikolsky]

I've made a few project changes and fixed all compiler warnings. The framework now can be used in a swift project as a module.

I included all public headers in the umbrella header, and made a few others private:

• CastServiceChannel because it has to import GoogleCast/GCKCastChannel.h;
• FireTVMediaControl because it has to import AmazonFling/MediaPlayerStatus.h;
• all ASIHTTPRequest classes because one of them requires zlib.h, and it's an outdated library anyway.

So the important question is to figure out what headers should really be public and hide everything else.