Using a new super evil hack solution on watchOS, solve the problem that aspectRatio does not works as expected.

This code by using the native UIView and logic by reverse engineering

SDWebImageSwiftUI/Classes/AnimatedImage.swift

@@ -14,12 +14,7 @@ import SDWebImageSwiftUIObjC
 
 // Convenient
 #if os(watchOS)
-public typealias AnimatedImageViewWrapper = SDAnimatedImageInterface
-extension SDAnimatedImageInterface {
-    var wrapped: SDAnimatedImageInterface {
-        return self
-    }
-}
+public typealias AnimatedImageViewWrapper = SDAnimatedImageInterfaceWrapper
 #endif
 
 // Coordinator Life Cycle Binding Object
@@ -562,19 +557,7 @@ extension AnimatedImage {
         var result = self
         result.aspectRatio = aspectRatio
         result.contentMode = contentMode
-        #if os(macOS) || os(iOS) || os(tvOS)
         return result.modifier(EmptyModifier()).aspectRatio(aspectRatio, contentMode: contentMode)
-        #else
-        return Group {
-            if aspectRatio != nil {
-                result.modifier(EmptyModifier()).aspectRatio(aspectRatio, contentMode: contentMode)
-            } else {
-                // on watchOS, there are no workaround like `AnimatedImageViewWrapper` to override `intrinsicContentSize`, so the aspect ratio is undetermined and cause sizing issues
-                // To workaround, we do not call default implementation for this case, using original solution instead
-                result
-            }
-        }
-        #endif
     }
 
     /// Constrains this view's dimensions to the aspect ratio of the given size.

SDWebImageSwiftUI/Classes/ObjC/SDAnimatedImageInterface.h

@@ -29,5 +29,13 @@ NS_ASSUME_NONNULL_BEGIN
 
 @end
 
+@interface SDAnimatedImageInterfaceWrapper : WKInterfaceGroup
+
+@property (nonatomic, strong, nonnull) SDAnimatedImageInterface *wrapped;
+
+- (instancetype)init WK_AVAILABLE_WATCHOS_ONLY(6.0);
+
+@end
+
 NS_ASSUME_NONNULL_END
 #endif

SDWebImageSwiftUI/Classes/ObjC/SDAnimatedImageInterface.m

@@ -9,25 +9,10 @@
 #import "SDAnimatedImageInterface.h"
 #if SD_WATCH
 
-#pragma mark - SPI
+#import <objc/runtime.h>
+#import <objc/message.h>
 
-static UIImage * SharedEmptyImage(void) {
-    // This is used for placeholder on `WKInterfaceImage`
-    // Do not using `[UIImage new]` because WatchKit will ignore it
-    static dispatch_once_t onceToken;
-    static UIImage *image;
-    dispatch_once(&onceToken, ^{
-        UIColor *color = UIColor.clearColor;
-        CGRect rect = WKInterfaceDevice.currentDevice.screenBounds;
-        UIGraphicsBeginImageContext(rect.size);
-        CGContextRef context = UIGraphicsGetCurrentContext();
-        CGContextSetFillColorWithColor(context, [color CGColor]);
-        CGContextFillRect(context, rect);
-        image = UIGraphicsGetImageFromCurrentImageContext();
-        UIGraphicsEndImageContext();
-    });
-    return image;
-}
+#pragma mark - SPI
 
 @protocol CALayerProtocol <NSObject>
 @property (nullable, strong) id contents;
@@ -43,6 +28,22 @@ static UIImage * SharedEmptyImage(void) {
 @property (nonatomic) CGFloat alpha;
 @property (nonatomic, getter=isHidden) BOOL hidden;
 @property (nonatomic, getter=isOpaque) BOOL opaque;
+@property (nonatomic) CGRect frame;
+@property (nonatomic) CGRect bounds;
+@property (nonatomic) CGPoint center;
+@property (nonatomic) BOOL clipsToBounds;
+@property (nonatomic, readonly) CGSize intrinsicContentSize;
+@property(nonatomic) NSInteger tag;
+
+- (void)invalidateIntrinsicContentSize;
+- (void)drawRect:(CGRect)rect;
+- (void)setNeedsDisplay;
+- (void)setNeedsDisplayInRect:(CGRect)rect;
+- (void)addSubview:(id<UIViewProtocol>)view;
+- (void)removeFromSuperview;
+- (void)layoutSubviews;
+- (CGSize)sizeThatFits:(CGSize)size;
+- (void)sizeToFit;
 
 @end
 
@@ -60,7 +61,7 @@ static UIImage * SharedEmptyImage(void) {
 // This is needed for dynamic created WKInterfaceObject, like `WKInterfaceMap`
 - (instancetype)_initForDynamicCreationWithInterfaceProperty:(NSString *)property;
 // This is remote UIView
-@property (nonatomic, strong, readonly) id<UIImageViewProtocol> _interfaceView;
+@property (nonatomic, strong, readwrite) id<UIViewProtocol> _interfaceView;
 
 @end
 
@@ -97,7 +98,6 @@ static UIImage * SharedEmptyImage(void) {
     return @{
         @"type" : @"image",
         @"property" : self.interfaceProperty,
-        @"image" : SharedEmptyImage()
     };
 }
 
@@ -113,8 +113,7 @@ static UIImage * SharedEmptyImage(void) {
     self.currentFrameIndex = 0;
     self.currentLoopCount = 0;
     
-    [super setImage:image];
-    [self _interfaceView].image = image;
+    ((id<UIImageViewProtocol>)[self _interfaceView]).image = image;
     if ([image.class conformsToProtocol:@protocol(SDAnimatedImage)]) {
         // Create animted player
         self.player = [SDAnimatedImagePlayer playerWithProvider:(id<SDAnimatedImage>)image];
@@ -257,5 +256,142 @@ static UIImage * SharedEmptyImage(void) {
     }];
 }
 
+@end
+
+
+#define SDAnimatedImageInterfaceWrapperTag 123456789
+#define SDAnimatedImageInterfaceWrapperSEL_layoutSubviews @"SDAnimatedImageInterfaceWrapper_layoutSubviews"
+#define SDAnimatedImageInterfaceWrapperSEL_sizeThatFits @" SDAnimatedImageInterfaceWrapper_sizeThatFits:"
+
+// This using hook to implements the same logic like AnimatedImageViewWrapper.swift
+static CGSize intrinsicContentSizeIMP(id<UIViewProtocol> self, SEL _cmd) {
+    struct objc_super superClass = {
+       self,
+       [self superclass]
+    };
+    NSUInteger tag = self.tag;
+    id<UIViewProtocol> interfaceView = self.subviews.firstObject;
+    if (tag != SDAnimatedImageInterfaceWrapperTag || !interfaceView) {
+        return ((CGSize(*)(id, SEL))objc_msgSendSuper)((__bridge id)(&superClass), _cmd);
+    }
+    CGSize size = interfaceView.intrinsicContentSize;
+    if (size.width > 0 && size.height > 0) {
+        CGFloat aspectRatio = size.height / size.width;
+        return CGSizeMake(1, 1 * aspectRatio);
+    } else {
+        return CGSizeMake(-1, -1);
+    }
+}
+
+static void layoutSubviewsIMP(id<UIViewProtocol> self, SEL _cmd) {
+    struct objc_super superClass = {
+       self,
+       [self superclass]
+    };
+    NSUInteger tag = self.tag;
+    id<UIViewProtocol> interfaceView = self.subviews.firstObject;
+    if (tag != SDAnimatedImageInterfaceWrapperTag || !interfaceView) {
+        ((void(*)(id, SEL))objc_msgSend)(self, NSSelectorFromString(SDAnimatedImageInterfaceWrapperSEL_layoutSubviews));
+        return;
+    }
+    ((void(*)(id, SEL))objc_msgSendSuper)((__bridge id)(&superClass), _cmd);
+    interfaceView.frame = self.bounds;
+}
+
+// This is suck that SwiftUI on watchOS will call extra sizeThatFits, we should always input size (already calculated with aspectRatio)
+// iOS's wrapper don't need this
+static CGSize sizeThatFitsIMP(id<UIViewProtocol> self, SEL _cmd, CGSize size) {
+    NSUInteger tag = self.tag;
+    id<UIViewProtocol> interfaceView = self.subviews.firstObject;
+    if (tag != SDAnimatedImageInterfaceWrapperTag || !interfaceView) {
+        return ((CGSize(*)(id, SEL))objc_msgSend)(self, NSSelectorFromString(SDAnimatedImageInterfaceWrapperSEL_sizeThatFits));
+    }
+    return size;
+}
+
+@implementation SDAnimatedImageInterfaceWrapper
+
++ (void)load {
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        Class class = NSClassFromString(@"SPInterfaceGroupView");
+        // Implements `intrinsicContentSize`
+        SEL selector = @selector(intrinsicContentSize);
+        Method method = class_getInstanceMethod(class, selector);
+
+        BOOL didAddMethod =
+            class_addMethod(class,
+                selector,
+                (IMP)intrinsicContentSizeIMP,
+                method_getTypeEncoding(method));
+        if (!didAddMethod) {
+            NSAssert(NO, @"SDAnimatedImageInterfaceWrapper will not work as expected.");
+        }
+        
+        // Override `layoutSubviews`
+        SEL originalSelector = @selector(layoutSubviews);
+        SEL swizzledSelector = NSSelectorFromString(SDAnimatedImageInterfaceWrapperSEL_layoutSubviews);
+        Method originalMethod = class_getInstanceMethod(class, originalSelector);
+        
+        didAddMethod =
+        class_addMethod(class,
+            swizzledSelector,
+            (IMP)layoutSubviewsIMP,
+            method_getTypeEncoding(originalMethod));
+        if (!didAddMethod) {
+            NSAssert(NO, @"SDAnimatedImageInterfaceWrapper will not work as expected.");
+        } else {
+            Method swizzledMethod = class_getInstanceMethod(class, swizzledSelector);
+            method_exchangeImplementations(originalMethod, swizzledMethod);
+        }
+        
+        // Override `sizeThatFits:`
+        originalSelector = @selector(sizeThatFits:);
+        swizzledSelector = NSSelectorFromString(SDAnimatedImageInterfaceWrapperSEL_sizeThatFits);
+        originalMethod = class_getInstanceMethod(class, originalSelector);
+        
+        didAddMethod =
+        class_addMethod(class,
+            swizzledSelector,
+            (IMP)sizeThatFitsIMP,
+            method_getTypeEncoding(originalMethod));
+        if (!didAddMethod) {
+            NSAssert(NO, @"SDAnimatedImageInterfaceWrapper will not work as expected.");
+        } else {
+            Method swizzledMethod = class_getInstanceMethod(class, swizzledSelector);
+            method_exchangeImplementations(originalMethod, swizzledMethod);
+        }
+    });
+}
+
+- (instancetype)init {
+    Class cls = [self class];
+    NSString *UUID = [NSUUID UUID].UUIDString;
+    NSString *property = [NSString stringWithFormat:@"%@_%@", cls, UUID];
+    self = [self _initForDynamicCreationWithInterfaceProperty:property];
+    if (self) {
+        self.wrapped = [[SDAnimatedImageInterface alloc] init];
+    }
+    return self;
+}
+
+- (NSDictionary *)interfaceDescriptionForDynamicCreation {
+    // This is called by WatchKit to provide default value
+    return @{
+        @"type" : @"group",
+        @"property" : self.interfaceProperty,
+        @"radius" : @(0),
+        @"items": @[self.wrapped.interfaceDescriptionForDynamicCreation], // This will create the native view and added to subview
+    };
+}
+
+- (void)set_interfaceView:(id<UIViewProtocol>)interfaceView {
+    // This is called by WatchKit when native view created
+    [super set_interfaceView:interfaceView];
+    // Bind the interface object and native view
+    interfaceView.tag = SDAnimatedImageInterfaceWrapperTag;
+    self.wrapped._interfaceView = interfaceView.subviews.firstObject;
+}
+
 @end
 #endif