diff --git a/Demo/Demo-iOS/ViewController.swift b/Demo/Demo-iOS/ViewController.swift
index 1240e34..5eb0978 100755
--- a/Demo/Demo-iOS/ViewController.swift
+++ b/Demo/Demo-iOS/ViewController.swift
@@ -23,11 +23,10 @@ class ViewController: UIViewController {
   }
 
   @IBAction func swapImage(_ sender: AnyObject) {
-    switch currentGIFName {
-    case "mugen":
-      currentGIFName = "earth"
-    default:
-      currentGIFName = "mugen"
+    let gifs = ["mugen", "earth", "nailed"]
+    if let index = gifs.firstIndex(of: currentGIFName) {
+      let nextIndex = (index + 1) % gifs.count
+      currentGIFName = gifs[nextIndex]
     }
   }
 
@@ -40,7 +39,7 @@ class ViewController: UIViewController {
   }
 
   func animate() {
-    imageView.animate(withGIFNamed: currentGIFName, animationBlock:  {
+    imageView.animate(withGIFNamed: currentGIFName, preparationBlock:  {
       DispatchQueue.main.async {
         self.imageDataLabel.text = self.currentGIFName.capitalized + " (\(self.imageView.frameCount) frames / \(String(format: "%.2f", self.imageView.gifLoopDuration))s)"
       }
diff --git a/Demo/Demo.xcodeproj/project.pbxproj b/Demo/Demo.xcodeproj/project.pbxproj
index cedf5c4..df8eccf 100755
--- a/Demo/Demo.xcodeproj/project.pbxproj
+++ b/Demo/Demo.xcodeproj/project.pbxproj
@@ -23,6 +23,8 @@
 		9D98823F19BC69CA00B790C6 /* ViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9D98823E19BC69CA00B790C6 /* ViewController.swift */; };
 		9D98824419BC69CA00B790C6 /* Images.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = 9D98824319BC69CA00B790C6 /* Images.xcassets */; };
 		9D98825A19BC69F600B790C6 /* Main.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = 9D98825919BC69F600B790C6 /* Main.storyboard */; };
+		A5D726E828B53C0800821347 /* earth.gif in Resources */ = {isa = PBXBuildFile; fileRef = A5D726E728B53C0800821347 /* earth.gif */; };
+		A5D726EC28B5599A00821347 /* nailed.gif in Resources */ = {isa = PBXBuildFile; fileRef = A5D726EB28B5599A00821347 /* nailed.gif */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXCopyFilesBuildPhase section */
@@ -59,6 +61,8 @@
 		9D98823E19BC69CA00B790C6 /* ViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ViewController.swift; sourceTree = "<group>"; };
 		9D98824319BC69CA00B790C6 /* Images.xcassets */ = {isa = PBXFileReference; lastKnownFileType = folder.assetcatalog; path = Images.xcassets; sourceTree = "<group>"; };
 		9D98825919BC69F600B790C6 /* Main.storyboard */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = file.storyboard; path = Main.storyboard; sourceTree = "<group>"; };
+		A5D726E728B53C0800821347 /* earth.gif */ = {isa = PBXFileReference; lastKnownFileType = image.gif; name = earth.gif; path = ../Tests/Images/earth.gif; sourceTree = SOURCE_ROOT; };
+		A5D726EB28B5599A00821347 /* nailed.gif */ = {isa = PBXFileReference; lastKnownFileType = image.gif; name = nailed.gif; path = ../Tests/Images/nailed.gif; sourceTree = SOURCE_ROOT; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -149,7 +153,9 @@
 		9D98823A19BC69CA00B790C6 /* Supporting Files */ = {
 			isa = PBXGroup;
 			children = (
+				A5D726E728B53C0800821347 /* earth.gif */,
 				002A1BFB1D1624D0005ABBD0 /* mugen.gif */,
+				A5D726EB28B5599A00821347 /* nailed.gif */,
 			);
 			path = "Supporting Files";
 			sourceTree = "<group>";
@@ -250,6 +256,8 @@
 			isa = PBXResourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				A5D726E828B53C0800821347 /* earth.gif in Resources */,
+				A5D726EC28B5599A00821347 /* nailed.gif in Resources */,
 				9D98824419BC69CA00B790C6 /* Images.xcassets in Resources */,
 				002A1BFC1D1624D0005ABBD0 /* mugen.gif in Resources */,
 				0032FE841FFA693500444203 /* LaunchScreen.storyboard in Resources */,
diff --git a/Gifu.xcodeproj/project.pbxproj b/Gifu.xcodeproj/project.pbxproj
index 4488d92..1303118 100644
--- a/Gifu.xcodeproj/project.pbxproj
+++ b/Gifu.xcodeproj/project.pbxproj
@@ -20,6 +20,7 @@
 		00B8C7961A3650EE00C188E7 /* Gifu.h in Headers */ = {isa = PBXBuildFile; fileRef = 00B8C7951A3650EE00C188E7 /* Gifu.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		00BF42CC1D99A1DC00C6F28D /* GIFAnimatable.swift in Sources */ = {isa = PBXBuildFile; fileRef = 00BF42CB1D99A1DC00C6F28D /* GIFAnimatable.swift */; };
 		00DD26EE1DA9643800A0F683 /* UIImageView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 00DD26ED1DA9643800A0F683 /* UIImageView.swift */; };
+		A5D726EA28B53D6400821347 /* earth.gif in Resources */ = {isa = PBXBuildFile; fileRef = A5D726E928B53D6400821347 /* earth.gif */; };
 		EAF49C7F1A3A4DE000B395DF /* UIImage.swift in Sources */ = {isa = PBXBuildFile; fileRef = EAF49C7E1A3A4DE000B395DF /* UIImage.swift */; };
 		EAF49CB11A3B6EEB00B395DF /* AnimatedFrame.swift in Sources */ = {isa = PBXBuildFile; fileRef = EAF49CB01A3B6EEB00B395DF /* AnimatedFrame.swift */; };
 /* End PBXBuildFile section */
@@ -52,6 +53,7 @@
 		00BF42CB1D99A1DC00C6F28D /* GIFAnimatable.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = GIFAnimatable.swift; sourceTree = "<group>"; };
 		00C50CFB2392BA9900CBE23C /* README.md */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = net.daringfireball.markdown; path = README.md; sourceTree = "<group>"; };
 		00DD26ED1DA9643800A0F683 /* UIImageView.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = UIImageView.swift; sourceTree = "<group>"; };
+		A5D726E928B53D6400821347 /* earth.gif */ = {isa = PBXFileReference; lastKnownFileType = image.gif; path = earth.gif; sourceTree = "<group>"; };
 		EAF49C7E1A3A4DE000B395DF /* UIImage.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = UIImage.swift; sourceTree = "<group>"; };
 		EAF49CB01A3B6EEB00B395DF /* AnimatedFrame.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = AnimatedFrame.swift; sourceTree = "<group>"; };
 /* End PBXFileReference section */
@@ -88,6 +90,7 @@
 		0036ABBA1BBD1D1700C6CC3D /* Images */ = {
 			isa = PBXGroup;
 			children = (
+				A5D726E928B53D6400821347 /* earth.gif */,
 				0036ABB61BBD1D0B00C6CC3D /* mugen.gif */,
 				0036ABB81BBD1D1400C6CC3D /* nailed.gif */,
 			);
@@ -271,6 +274,7 @@
 			files = (
 				0036ABB71BBD1D0B00C6CC3D /* mugen.gif in Resources */,
 				0036ABB91BBD1D1400C6CC3D /* nailed.gif in Resources */,
+				A5D726EA28B53D6400821347 /* earth.gif in Resources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};