Implemented Subspec for Remote Fetch Support

Example/Podfile

@@ -3,4 +3,5 @@ use_frameworks!
 
 target 'Demo' do
   pod 'ImageViewer.swift', :path => './../'
-end
+  pod 'ImageViewer.swift/Fetcher', :path => './../'
+end

Example/Podfile.lock

@@ -1,12 +1,14 @@
 PODS:
-  - ImageViewer.swift (3.0):
+  - ImageViewer.swift (3.0)
+  - ImageViewer.swift/Fetcher (3.0):
     - SDWebImage
-  - SDWebImage (5.3.3):
-    - SDWebImage/Core (= 5.3.3)
-  - SDWebImage/Core (5.3.3)
+  - SDWebImage (5.8.4):
+    - SDWebImage/Core (= 5.8.4)
+  - SDWebImage/Core (5.8.4)
 
 DEPENDENCIES:
   - ImageViewer.swift (from `./../`)
+  - ImageViewer.swift/Fetcher (from `./../`)
 
 SPEC REPOS:
   trunk:
@@ -17,9 +19,9 @@ EXTERNAL SOURCES:
     :path: "./../"
 
 SPEC CHECKSUMS:
-  ImageViewer.swift: a8ddca1afeea736c557ba44ce5c220d829922c8a
-  SDWebImage: 51ab1ce3ebd20dec6665ae8ba25c928da323db41
+  ImageViewer.swift: 5a7de1366351c307023daf71f907dedee968b5d0
+  SDWebImage: cf6922231e95550934da2ada0f20f2becf2ceba9
 
-PODFILE CHECKSUM: 3cb622a244c4948f6d66f0aaa9d36294c3ab7fe1
+PODFILE CHECKSUM: e724d0d4011b46b198571c9f9ed6734d40b74bc4
 
-COCOAPODS: 1.8.4
+COCOAPODS: 1.9.3

ImageViewer.swift.podspec

@@ -10,7 +10,6 @@ Pod::Spec.new do |s|
   }
   s.source_files = 'Sources/*'
   s.requires_arc = true
-  s.dependency 'SDWebImage'
   s.ios.deployment_target  = '10.0'
   s.swift_versions = ['4.0','4.2','5.0']
   s.license = {
@@ -26,4 +25,9 @@ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLI
 
 LICENSE
   }
-end
+
+  s.default_subspecs = :none
+  s.subspec 'Fetcher' do |cs|
+    cs.dependency 'SDWebImage'
+  end
+end

README.md

@@ -27,6 +27,13 @@ Using [cocoapods](https://cocoapods.org)
 pod 'ImageViewer.swift', '~> 3.0'
 ```
 
+If you need remote image fetching:
+
+```ruby
+pod 'ImageViewer.swift', '~> 3.0'
+pod 'ImageViewer.swift/Fetcher', '~> 3.0'
+```
+
 ## How to use it
 
 The simplest way to to use this is by using the [imageView.setupImageViewer()](https://github.com/michaelhenry/MHFacebookImageViewer/blob/master/Example/Demo/BasicViewController.swift#L11)

Sources/ImageItem.swift

@@ -2,5 +2,7 @@ import UIKit
 
 public enum ImageItem {
     case image(UIImage?)
+    #if canImport(SDWebImage)
     case url(URL, placeholder: UIImage?)
+    #endif
 }

Sources/ImageViewerController.swift

@@ -1,5 +1,7 @@
 import UIKit
+#if canImport(SDWebImage)
 import SDWebImage
+#endif
 
 protocol ImageViewerControllerDelegate:class {
     func imageViewerDidClose(_ imageViewer: ImageViewerController)
@@ -90,6 +92,7 @@ class ImageViewerController:UIViewController, UIGestureRecognizerDelegate {
         case .image(let img):
             imageView.image = img
             imageView.layoutIfNeeded()
+        #if canImport(SDWebImage)
         case .url(let url, let placeholder):
             imageView.sd_setImage(
                 with: url,
@@ -102,6 +105,7 @@ class ImageViewerController:UIViewController, UIGestureRecognizerDelegate {
                         }
                     }
                 }
+        #endif
         default:
             break
         }

Sources/UIImageView_Extensions.swift

@@ -22,6 +22,7 @@ extension UIImageView {
         setup(datasource: nil, options: options, from: from)
     }
 
+    #if canImport(SDWebImage)
     public func setupImageViewer(
         url:URL,
         initialIndex:Int = 0,
@@ -39,6 +40,7 @@ extension UIImageView {
             options: options,
             from: from)
     }
+    #endif
 
     public func setupImageViewer(
         images:[UIImage],
@@ -57,6 +59,7 @@ extension UIImageView {
             from: from)
     }
 
+    #if canImport(SDWebImage)
     public func setupImageViewer(
         urls:[URL],
         initialIndex:Int = 0,
@@ -74,6 +77,7 @@ extension UIImageView {
             options: options,
             from: from)
     }
+    #endif
 
     public func setupImageViewer(
         datasource:ImageDataSource,