jeffreycamealy · jomisj · May 1, 2014
diff --git a/ChangingBackground.xcodeproj/project.pbxproj b/ChangingBackground.xcodeproj/project.pbxproj
@@ -24,6 +24,8 @@
 		001809EC171C6764002D3E93 /* blue@2x.png in Resources */ = {isa = PBXBuildFile; fileRef = 001809E8171C6764002D3E93 /* blue@2x.png */; };
 		001809ED171C6764002D3E93 /* green.png in Resources */ = {isa = PBXBuildFile; fileRef = 001809E9171C6764002D3E93 /* green.png */; };
 		001809EE171C6764002D3E93 /* green@2x.png in Resources */ = {isa = PBXBuildFile; fileRef = 001809EA171C6764002D3E93 /* green@2x.png */; };
+		67B6165F1912C21100E08AC1 /* UINavigationController+CustomTransition.m in Sources */ = {isa = PBXBuildFile; fileRef = 67B6165E1912C21100E08AC1 /* UINavigationController+CustomTransition.m */; };
+		67B616631912C3D100E08AC1 /* QuartzCore.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 67B616621912C3D100E08AC1 /* QuartzCore.framework */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXFileReference section */
@@ -50,13 +52,17 @@
 		001809E8171C6764002D3E93 /* blue@2x.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = "blue@2x.png"; sourceTree = "<group>"; };
 		001809E9171C6764002D3E93 /* green.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = green.png; sourceTree = "<group>"; };
 		001809EA171C6764002D3E93 /* green@2x.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = "green@2x.png"; sourceTree = "<group>"; };
+		67B6165D1912C21100E08AC1 /* UINavigationController+CustomTransition.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "UINavigationController+CustomTransition.h"; sourceTree = "<group>"; };
+		67B6165E1912C21100E08AC1 /* UINavigationController+CustomTransition.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = "UINavigationController+CustomTransition.m"; sourceTree = "<group>"; };
+		67B616621912C3D100E08AC1 /* QuartzCore.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = QuartzCore.framework; path = System/Library/Frameworks/QuartzCore.framework; sourceTree = SDKROOT; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
 		001809B2171C637E002D3E93 /* Frameworks */ = {
 			isa = PBXFrameworksBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				67B616631912C3D100E08AC1 /* QuartzCore.framework in Frameworks */,
 				001809B9171C637E002D3E93 /* UIKit.framework in Frameworks */,
 				001809BB171C637E002D3E93 /* Foundation.framework in Frameworks */,
 				001809BD171C637E002D3E93 /* CoreGraphics.framework in Frameworks */,
@@ -86,6 +92,7 @@
 		001809B7171C637E002D3E93 /* Frameworks */ = {
 			isa = PBXGroup;
 			children = (
+				67B616621912C3D100E08AC1 /* QuartzCore.framework */,
 				001809B8171C637E002D3E93 /* UIKit.framework */,
 				001809BA171C637E002D3E93 /* Foundation.framework */,
 				001809BC171C637E002D3E93 /* CoreGraphics.framework */,
@@ -96,6 +103,7 @@
 		001809BE171C637E002D3E93 /* ChangingBackground */ = {
 			isa = PBXGroup;
 			children = (
+				67B6165C1912C1A100E08AC1 /* Categories */,
 				001809EF171C6768002D3E93 /* BackgroundImages */,
 				001809D5171C63FC002D3E93 /* AppDelegate */,
 				001809DC171C6453002D3E93 /* ViewControllers */,
@@ -167,6 +175,15 @@
 			name = BackgroundImages;
 			sourceTree = "<group>";
 		};
+		67B6165C1912C1A100E08AC1 /* Categories */ = {
+			isa = PBXGroup;
+			children = (
+				67B6165D1912C21100E08AC1 /* UINavigationController+CustomTransition.h */,
+				67B6165E1912C21100E08AC1 /* UINavigationController+CustomTransition.m */,
+			);
+			name = Categories;
+			sourceTree = "<group>";
+		};
 /* End PBXGroup section */
 
 /* Begin PBXNativeTarget section */
@@ -241,6 +258,7 @@
 				001809C5171C637E002D3E93 /* main.m in Sources */,
 				001809C9171C637E002D3E93 /* AppDelegate.m in Sources */,
 				001809D9171C6448002D3E93 /* FirstViewController.m in Sources */,
+				67B6165F1912C21100E08AC1 /* UINavigationController+CustomTransition.m in Sources */,
 				001809E0171C64E4002D3E93 /* SecondViewController.m in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
@@ -356,6 +374,7 @@
 				001809D4171C637E002D3E93 /* Release */,
 			);
 			defaultConfigurationIsVisible = 0;
+			defaultConfigurationName = Release;
 		};
 /* End XCConfigurationList section */
 	};

diff --git a/ChangingBackground/AppDelegate.h b/ChangingBackground/AppDelegate.h
@@ -10,4 +10,7 @@
 
 @interface AppDelegate : UIResponder <UIApplicationDelegate>
 
+- (void)fadeFromBlueToGreenImage;
+- (void)fadeFromGreenToBlueImage;
+
 @end
diff --git a/ChangingBackground/AppDelegate.m b/ChangingBackground/AppDelegate.m
@@ -12,6 +12,11 @@
 @interface AppDelegate () {
     UIWindow *window;
 }
+
+//These UIImageView properties will be added as subviews of window
+@property (nonatomic, strong) UIImageView* blueBGImageView;
+@property (nonatomic, strong) UIImageView* greenBGImageView;
+
 @end
 
 
@@ -21,7 +26,21 @@ - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(
     window = [UIWindow.alloc initWithFrame:UIScreen.mainScreen.bounds];
     [window makeKeyAndVisible];
 
+    //Adding an imageView with the Green image as a subview of window
+    self.greenBGImageView = [[UIImageView alloc]initWithFrame:[[UIScreen mainScreen] bounds]];
+    [self.greenBGImageView setImage:[UIImage imageNamed:@"green.png"]];
+    [window addSubview:self.greenBGImageView];
+
+    //Adding an imageView with the Blue image as a subview of window (on top of greenImageView)
+    self.blueBGImageView = [[UIImageView alloc]initWithFrame:[[UIScreen mainScreen] bounds]];
+    [self.blueBGImageView setImage:[UIImage imageNamed:@"blue.png"]];
+    [window addSubview:self.blueBGImageView];
+
     FirstViewController *firstViewController = FirstViewController.new;
+
+    //Making the background color of FirstViewController clearColor so that the imageViews added as subviews of window can be seen.
+    [firstViewController.view setBackgroundColor:[UIColor clearColor]];
+
     UINavigationController *navigationController = [UINavigationController.alloc initWithRootViewController:firstViewController];
     [navigationController setNavigationBarHidden:YES];
 
@@ -30,4 +49,30 @@ - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(
     return YES;
 }
 
+// UIView animation changes the alpha of the blueImageView from current value to 0.0 (fully transparent)
+// This reveals the greenImageView behind the blueImageView
+- (void)fadeFromBlueToGreenImage
+{
+    [UIView animateWithDuration:2.5
+                          delay:0.0
+                        options:UIViewAnimationOptionBeginFromCurrentState
+                     animations:^{
+                         self.blueBGImageView.alpha = 0.0;
+                     }
+                     completion:nil];
+}
+
+// UIView animation changes the alpha of the blueImageView from current value to 1.0 (fully opaque)
+// This hides the greenImageView behind the blueImageView
+- (void)fadeFromGreenToBlueImage
+{
+    [UIView animateWithDuration:2.5
+                          delay:0.0
+                        options:UIViewAnimationOptionBeginFromCurrentState
+                     animations:^{
+                         self.blueBGImageView.alpha = 1.0;
+                     }
+                     completion:nil];
+}
+
 @end
diff --git a/ChangingBackground/ChangingBackground-Prefix.pch b/ChangingBackground/ChangingBackground-Prefix.pch
@@ -11,4 +11,8 @@
 #ifdef __OBJC__
     #import <UIKit/UIKit.h>
     #import <Foundation/Foundation.h>
+    #import "AppDelegate.h"
 #endif
+
+//Adding a Macro to access the AppDelegate easily in other programs
+#define APPDELEGATE ((AppDelegate*)[[UIApplication sharedApplication] delegate])
diff --git a/ChangingBackground/FirstViewController.m b/ChangingBackground/FirstViewController.m
@@ -8,6 +8,7 @@
 
 #import "FirstViewController.h"
 #import "SecondViewController.h"
+#import "UINavigationController+CustomTransition.h"
 
 @interface FirstViewController ()
 
@@ -17,7 +18,11 @@ @implementation FirstViewController
 
 - (IBAction)goForwardButtonPressed {
     SecondViewController *secondViewController = SecondViewController.new;
-    [self.navigationController pushViewController:secondViewController animated:YES];
+
+    //Using the customTransiton method from UINavigationController's CustomTransition category
+    [self.navigationController pushViewControllerWithCustomTansition:secondViewController];
+
+    [APPDELEGATE fadeFromBlueToGreenImage];
 }
 
 @end