negate logic to actually do what the function implies.

Aspects.m

@@ -133,9 +133,9 @@ static SEL aspect_aliasForSelector(SEL selector) {
 #pragma mark - Class + Selector Preparation
 
 static BOOL aspect_isMsgForwardIMP(IMP impl) {
-    return impl != _objc_msgForward
+    return impl == _objc_msgForward
 #if !defined(__arm64__)
-    && impl != (IMP)_objc_msgForward_stret
+    || impl == (IMP)_objc_msgForward_stret
 #endif
     ;
 }
@@ -162,7 +162,7 @@ static void aspect_prepareClassAndHookSelector(NSObject *self, SEL selector, NSE
     Class klass = aspect_hookClass(self, error);
     Method targetMethod = class_getInstanceMethod(klass, selector);
     IMP targetMethodIMP = method_getImplementation(targetMethod);
-    if (aspect_isMsgForwardIMP(targetMethodIMP)) {
+    if (!aspect_isMsgForwardIMP(targetMethodIMP)) {
         // Make a method alias for the existing method implementation, it not already copied.
         const char *typeEncoding = method_getTypeEncoding(targetMethod);
         SEL aliasSelector = aspect_aliasForSelector(selector);
@@ -191,7 +191,7 @@ static void aspect_cleanupHookedClassAndSelector(NSObject *self, SEL selector) {
     // Check if the method is marked as forwarded and undo that.
     Method targetMethod = class_getInstanceMethod(klass, selector);
     IMP targetMethodIMP = method_getImplementation(targetMethod);
-    if (aspect_isMsgForwardIMP(targetMethodIMP)) {
+    if (!aspect_isMsgForwardIMP(targetMethodIMP)) {
         // Restore the original method implementation.
         const char *typeEncoding = method_getTypeEncoding(targetMethod);
         SEL aliasSelector = aspect_aliasForSelector(selector);