macos - cgeventtap 的 Apple mach-o 链接器 ID 错误

Question

我正在尝试使 CGEventTap 工作。我认为我已经正确完成了所有操作，但是当我运行时出现此错误:

Apple Mach-O Linker (id) Error

Undefined symbols for architecture x86_64:
  "_tapCallback", referenced from:
      -[TestAppDelegate applicationDidFinishLaunching:] in TestAppDelegate.o
ld: symbol(s) not found for architecture x86_64
collect2: ld returned 1 exit status

Answer 1

听起来您已经定义了 tapCallback() 函数，但尚未实际实现它。换句话说，您的 TestAppDelegate 类可能如下所示:

#import "TestAppDelegate.h"

CGEventRef tapCallback(CGEventTapProxy proxy,
            CGEventType type,
           CGEventRef event,
              void *userInfo);


@implementation TestAppDelegate

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
    CFMachPortRef eventTapRef = CGEventTapCreate(kCGSessionEventTap, 
                                                 kCGTailAppendEventTap,
                                                 kCGEventTapOptionListenOnly,
                                                 kCGEventMaskForAllEvents,
                                                 tapCallback,
                                                 NULL);
    // additional code

}

@end

在某个地方，您需要实际实现 tapCallback() 函数。如果您实际上已经实现了它，例如在另一个文件中，请确保该文件包含在您构建的目标中。

否则，执行类似的操作应该允许程序运行:

CGEventRef tapCallback(CGEventTapProxy proxy,
                             CGEventType type,
                                CGEventRef event,
                                   void *userInfo) {
    NSLog(@"tapCallback()");
    return event;
}