Add Swift Package Manager Support

[maxep]

Issue Link :link:

Fixes #77

Goals :soccer:

Add support of Swift Package Manager.

Implementation Details :construction:

• As ClusterKit is implemented in objc, the project needs to follow the C library structure:

  . 
  ├── Package.swift
  └── Sources 
       └── ClusterKit
         ├── **/*.m
         └── include 
           ├── ClusterKit 
           | └── *.h
           └── module.modulemap

• In order to be built by swift build (macOS), UIKit availability has to be checked using compile fag:

  #if __has_include(<UIKit/UIKit.h>)
  ...
  #endif

• Replace #import "*.h" with module import #import <ClusterKit/*.h>.

Testing Details :mag:

Test suite is not yet available at swift test, tests will need to be re-rewritten in swift.

[carbonimax]

It's all good but mapView.clusterManager seems to be not exposed to swift.

[maxep]

@carbonimax It's using a custom module.modulemap for SPM. You need to import the submodule:

import ClusterKit.MapKit

[carbonimax]

I missed it! It works

[thothai94]

How can I import this ClusterKit package to use with Mapbox? "import ClusterKit.Mapbox" or "import ClusterKit" always cause error "Value of type 'MGLMapView' has no member 'clusterManager'"