feat: feat: swizzled on app will appear

Sources/Amplitude/Amplitude.m

@@ -543,6 +543,7 @@ - (void)initializeApiKey:(NSString *)apiKey
             // Unlike other default events options that can be evaluated later, screenViews has to be evaluated during the actual initialization
             if (self.defaultTracking.screenViews) {
                 [UIViewController amp_swizzleViewDidAppear];
+                [UIViewController amp_swizzleViewWillAppear];
             }
 #endif
         }];

Sources/Amplitude/UIViewController+AMPScreen.h

@@ -27,6 +27,7 @@
 @interface UIViewController (AMPScreen)
 
 + (void)amp_swizzleViewDidAppear;
++ (void)amp_swizzleViewWillAppear;
 + (UIViewController *)amp_rootViewControllerFromView:(UIView *)view;
 + (UIViewController *)amp_topViewController:(UIViewController *)rootViewController;
 

Sources/Amplitude/UIViewController+AMPScreen.m

@@ -39,9 +39,6 @@
 #import "AMPConstants.h"
 #import <UIKit/UIKit.h>
 
-static NSNotificationName const __UIWindowSceneDidChangeScreenNotification = @"__UIWindowSceneDidChangeScreenNotification";
-
-
 #if !TARGET_OS_OSX && !TARGET_OS_WATCH
 
 
@@ -75,6 +72,35 @@ + (void)amp_swizzleViewDidAppear {
     });
 }
 
++ (void)amp_swizzleViewWillAppear {
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        Class class = [self class];
+
+        SEL originalSelector = @selector(viewWillAppear:);
+        SEL swizzledSelector = @selector(amp_viewWillAppear:);
+
+        Method originalMethod = class_getInstanceMethod(class, originalSelector);
+        Method swizzledMethod = class_getInstanceMethod(class, swizzledSelector);
+
+        BOOL didAddMethod =
+            class_addMethod(class,
+                            originalSelector,
+                            method_getImplementation(swizzledMethod),
+                            method_getTypeEncoding(swizzledMethod));
+
+        if (didAddMethod) {
+            class_replaceMethod(class,
+                                swizzledSelector,
+                                method_getImplementation(originalMethod),
+                                method_getTypeEncoding(originalMethod));
+        } else {
+            method_exchangeImplementations(originalMethod, swizzledMethod);
+        }
+    });
+}
+
+
 
 + (UIViewController *)amp_rootViewControllerFromView:(UIView *)view {
     UIViewController *root = view.window.rootViewController;
@@ -120,7 +146,8 @@ + (UIViewController *)amp_nextRootViewController:(UIViewController *)rootViewCon
     return nil;
 }
 
-- (void)amp_viewDidAppear:(BOOL)animated {
+
+- (void)amp_viewWillAppear:(BOOL)animated {
     AMPLITUDE_LOG(@"self is %@", self);
     UIViewController *top = [[self class] amp_rootViewControllerFromView:self.view];
     if (!top) {
@@ -137,13 +164,57 @@ - (void)amp_viewDidAppear:(BOOL)animated {
             name = @"Unknown";
         }
     }
+
+    NSLog(@"**********view will appear**********");
+    //NSLog(@"Screen changed!");
+
+    printViewHierarchy(self.view, 0);
+
+/*
+    UIGraphicsBeginImageContextWithOptions(self.view.bounds.size, self.view.opaque, 0.0f);
+    [self.view drawViewHierarchyInRect:self.view.bounds afterScreenUpdates:NO];
+    UIImage *snapshotImageFromMyView = UIGraphicsGetImageFromCurrentImageContext();
+    UIGraphicsEndImageContext();
+*/
+
+    [[Amplitude instance] logEvent:kAMPScreenViewed withEventProperties:@{
+        kAMPEventPropScreenName: name ?: @"",
+    }];
+
+    // call original method, this is not recurrsive method call
+    [self amp_viewWillAppear:animated];
+}
+
+- (void)amp_viewDidAppear:(BOOL)animated {
+    AMPLITUDE_LOG(@"self is %@", self);
+    UIViewController *top = [[self class] amp_rootViewControllerFromView:self.view];
+    if (!top) {
+        AMPLITUDE_LOG(@"Failed to infer screen");
+        return;
+    }
 
-    [[NSNotificationCenter defaultCenter] addObserver:self
-                                             selector:@selector(screenChanged:)
-                                                 name:__UIWindowSceneDidChangeScreenNotification
-                                               object:nil];
+    NSString *name = [top title];
+    if (!name || name.length == 0) {
+        // if no class title found, try view controller's description
+        name = [[[top class] description] stringByReplacingOccurrencesOfString:@"ViewController" withString:@""];
+        if (name.length == 0) {
+            AMPLITUDE_LOG(@"Failed to infer screen name");
+            name = @"Unknown";
+        }
+    }
+
+    NSLog(@"**********View did appear**********");
+    //NSLog(@"Screen changed!");
 
+    printViewHierarchy(self.view, 0);
 
+/*
+    UIGraphicsBeginImageContextWithOptions(self.view.bounds.size, self.view.opaque, 0.0f);
+    [self.view drawViewHierarchyInRect:self.view.bounds afterScreenUpdates:NO];
+    UIImage *snapshotImageFromMyView = UIGraphicsGetImageFromCurrentImageContext();
+    UIGraphicsEndImageContext();
+*/
+
     [[Amplitude instance] logEvent:kAMPScreenViewed withEventProperties:@{
         kAMPEventPropScreenName: name ?: @"",
     }];
@@ -152,12 +223,16 @@ - (void)amp_viewDidAppear:(BOOL)animated {
     [self amp_viewDidAppear:animated];
 }
 
-- (void)screenChanged:(NSNotification *)notification {
+/*
+ [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(screenChanged:) name:@"screenChanged" object:nil];
+ //UIAccessibilityScreenChangedNotification
+
+ - (void)screenChanged:(NSNotification *)notification {
     // Handle the screen change here
     NSLog(@"**********Before print view hierarchy**********");
     NSLog(@"Screen changed!");
     printViewHierarchy(self.view, 0);
-}
+}*/
 
 void printViewHierarchy(UIView *view, int indent) {
     NSMutableString *indentation = [NSMutableString string];
@@ -170,6 +245,6 @@ void printViewHierarchy(UIView *view, int indent) {
         printViewHierarchy(subview, indent + 4);
     }
 }
-
+// city of staff person.
 @end
 #endif