Compatible with both swift 2.2 and 2.3

.travis.yml

@@ -25,4 +25,5 @@ after_success:
     if [ "$TEST_TYPE" = iOS ] || [ "$TEST_TYPE" = OSX ] || [ "$TEST_TYPE" = tvOS ]; then
       bash <(curl -s https://codecov.io/bash)
     fi
-    sleep 5
+    sleep 10
+    

Sources/Image.swift

@@ -168,7 +168,11 @@ func ImagePNGRepresentation(image: Image) -> NSData? {
 #if os(OSX)
     if let cgimage = image.CGImage {
         let rep = NSBitmapImageRep(CGImage: cgimage)
+        #if swift(>=2.3)
         return rep.representationUsingType(.PNG, properties:[:])
+        #else
+        return rep.representationUsingType(.NSPNGFileType, properties:[:])
+        #endif
     }
     return nil
 #else
@@ -180,7 +184,11 @@ func ImagePNGRepresentation(image: Image) -> NSData? {
 func ImageJPEGRepresentation(image: Image, _ compressionQuality: CGFloat) -> NSData? {
 #if os(OSX)
     let rep = NSBitmapImageRep(CGImage: image.CGImage)
-    return rep.representationUsingType(.JPEG, properties: [NSImageCompressionFactor: compressionQuality])
+    #if swift(>=2.3)
+        return rep.representationUsingType(.JPEG, properties: [NSImageCompressionFactor: compressionQuality])
+    #else
+        return rep.representationUsingType(.NSJPEGFileType, properties: [NSImageCompressionFactor: compressionQuality])
+    #endif
 #else
     return UIImageJPEGRepresentation(image, compressionQuality)
 #endif

Sources/ImageDownloader.swift

@@ -285,7 +285,12 @@ extension ImageDownloader {
         self.requestModifier?(request)
         
         // There is a possiblility that request modifier changed the url to `nil` or empty.
-        if request.URL == nil || request.URL?.absoluteString == nil || (request.URL?.absoluteString?.isEmpty)! {
+        #if swift(>=2.3)
+        let isEmptyUrl = (request.URL == nil || request.URL!.absoluteString == nil || (request.URL!.absoluteString!.isEmpty))
+        #else
+        let isEmptyUrl = (request.URL == nil || request.URL!.absoluteString.isEmpty)
+        #endif
+        if isEmptyUrl {
             completionHandler?(image: nil, error: NSError(domain: KingfisherErrorDomain, code: KingfisherError.InvalidURL.rawValue, userInfo: nil), imageURL: nil, originalData: nil)
             return nil
         }

Sources/ImageView+Kingfisher.swift

@@ -219,7 +219,12 @@ extension ImageView {
                     
 #if os(OSX)
                     let indicator = NSProgressIndicator(frame: CGRect(x: 0, y: 0, width: 16, height: 16))
+    
+                    #if swift(>=2.3)
                     indicator.controlSize = .Small
+                    #else
+                    indicator.controlSize = .SmallControlSize
+                    #endif
                     indicator.style = .SpinningStyle
 #else
     #if os(tvOS)

Sources/Resource.swift

@@ -49,6 +49,10 @@ public struct Resource {
      */
     public init(downloadURL: NSURL, cacheKey: String? = nil) {
         self.downloadURL = downloadURL
+        #if swift(>=2.3)
         self.cacheKey = cacheKey ?? downloadURL.absoluteString!
+        #else
+        self.cacheKey = cacheKey ?? downloadURL.absoluteString
+        #endif
     }
 }

Tests/KingfisherTests/ImagePrefetcherTests.swift

@@ -76,7 +76,11 @@ class ImagePrefetcherTests: XCTestCase {
                 XCTAssertEqual(completedResources.count, urls.count, "All resources prefetching should be completed.")
                 XCTAssertEqual(progressCalledCount, urls.count, "Progress should be called the same time of download count.")
                 for url in urls {
+                    #if swift(>=2.3)
                     XCTAssertTrue(KingfisherManager.sharedManager.cache.isImageCachedForKey(url.absoluteString!).cached)
+                    #else
+                    XCTAssertTrue(KingfisherManager.sharedManager.cache.isImageCachedForKey(url.absoluteString).cached)
+                    #endif
                 }
         }