AXUIElementCopyAttributeValue failed: kAXErrorCannotComplete

I'm trying to write a program where I want to get the text content selected by the mouse by detecting mouse movements. My main code is as follows:

#import "AppDelegate.h"
#import <Cocoa/Cocoa.h>

@interface AppDelegate ()

@property (strong) IBOutlet NSWindow *window;
@property (nonatomic) CFMachPortRef eventTap;

@end

CGEventRef myCGEventCallback(CGEventTapProxy proxy, CGEventType type, CGEventRef event, void *refcon) {

    if (type == kCGEventLeftMouseDown) {
        NSLog(@"Mouse down.");
    }
    else if (type == kCGEventLeftMouseUp) {
        NSLog(@"Mouse up.");
        
        NSRunningApplication *currentApp = [[NSWorkspace sharedWorkspace] frontmostApplication];
        AXUIElementRef appElement = AXUIElementCreateApplication(currentApp.processIdentifier);

        AXUIElementRef windowElement;
        AXError error = AXUIElementCopyAttributeValue(appElement, kAXFocusedWindowAttribute, (CFTypeRef *)&windowElement);
        if (error != kAXErrorSuccess) {
            NSLog(@"Could not get focused window. Error code: %d", error);
            return event;
        }

        AXValueRef selectedTextValue;
        error = AXUIElementCopyAttributeValue(windowElement, kAXSelectedTextAttribute, (CFTypeRef *)&selectedTextValue);
        if (error != kAXErrorSuccess) {
            NSLog(@"Could not get selected text. Error code: %d", error);
            return event;
        }

        NSString *selectedText = (__bridge_transfer NSString *)selectedTextValue;
        NSLog(@"Selected text: %@", selectedText);
    }

    return event;
}

@implementation AppDelegate

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
    // Insert code here to initialize your application
    
    self.eventTap = CGEventTapCreate(kCGSessionEventTap, kCGHeadInsertEventTap, 0, CGEventMaskBit(kCGEventLeftMouseDown) | CGEventMaskBit(kCGEventLeftMouseUp), myCGEventCallback, NULL);

    if (self.eventTap) {
        
        CFRunLoopSourceRef runLoopSource = CFMachPortCreateRunLoopSource(kCFAllocatorDefault, self.eventTap, 0);
        CFRunLoopAddSource(CFRunLoopGetCurrent(), runLoopSource, kCFRunLoopCommonModes);

        CGEventTapEnable(self.eventTap, true);
        CFRelease(runLoopSource);
        // Don't release eventTap here
        
    } else {
        NSLog(@"Failed to create event tap");
    }
}


- (void)applicationWillTerminate:(NSNotification *)aNotification {
    // Insert code here to tear down your application
    if (self.eventTap) {
        CFRelease(self.eventTap);
    }
}


- (BOOL)applicationSupportsSecureRestorableState:(NSApplication *)app {
    return YES;
}

@end

I confirmed that I have granted "Accessibility" permissions to my program and the application I am trying to access is xcode or when I try to access the chrome interface I get the same error kAXErrorCannotComplete. So how do I deal with this problem? Or is there any other way to achieve my target function?

PS: I solved the above error by set App Sandbox Value (NO) in the entitlements, but I don't know if this is a reasonable solution. And then AXUIElementCopyAttributeValue generated another error kAXErrorFailure. How should I troubleshoot this problem ？