Add Xcode 7 lightweight generics to make Swift use easier

[iosdevzone]

This PR adds Xcode 7 lightweight generic annotations to various .h files. This makes the library much more pleasant to use in Swift and also adds some compiler checking (during the process I discovered that -[XCProject configurationWithName] had an incorrect return type!)

I did not propagate the annotated types to the .m files since it appears the compiler ignores them (e.g. you can add a different annotation in the .m file and the compiler and static analyzer do not complain).

Since these annotations are only available in Xcode 7 perhaps they should not be merged onto master? It would break builds for folks still on Xcode 6.

[jasperblues]

Hello @iosdevzone

Are these backward compatible? (I haven't tried OC generics yet - super happy when they were announced though)

Is this backward backward compatible? If not, I want to tag a new .x version and push that to cocoapods as the final, and start a new major version.

Thanks so much for this 🍻

[iosdevzone]

Hi Jasper,
Code containing lightweight generics is only compilable with Xcode 7, but they do not require runtime support, so you can set your deployment target to earlier versions of the OS. So they are not backward compatible at compile time but are a runtime.
If you wanted to keep the codebase compilable with older versions of Xcode we could do something like this.

#if __has_feature(objc_generics)
#define NSARRAY_OF(x) NSArray<x>
#define NSDICTIONARY_OF(x,y) NSDictionary<x,y>
#else
#define NSARRAY_OF(x) NSArray
#define NSDICTIONARY_OF(x,y) NSDictionary
#endif

Then in the object interfaces use something like:

@interface ViewController : UIViewController

@property (nonatomic) NSARRAY_OF(NSString*) *objects;
@property (nonatomic) NSDICTIONARY_OF(NSString*,NSString*) *stringToString;
@end

This approach might simplify fixing bugs in the future (i.e. you would not need to back port them). You probably have a better idea what users of the library want or need so I will defer to your judgement on this.

Cheer,
Danny

[jasperblues]

OK, let's just tell folks on older versions to use either a static library, or the last .x version. I'll tag the final .x now and merge this as a new version.

[jasperblues]

Merged @iosdevzone - thanks so much. Sorry for the delay.

[iosdevzone]

Thanks. I hope folks find the changes useful!