在Objective-C，简单的答案，用少量可可和大多Carbon Accessibility API是：

// Get the process ID of the frontmost application.

NSRunningApplication* app = [[NSWorkspace sharedWorkspace]

frontmostApplication];

pid_t pid = [app processIdentifier];

// See if we have accessibility permissions, and if not, prompt the user to

// visit System Preferences.

NSDictionary *options = @{(id)kAXTrustedCheckOptionPrompt: @YES};

Boolean appHasPermission = AXIsProcessTrustedWithOptions(

(__bridge CFDictionaryRef)options);

if (!appHasPermission) {

return; // we don't have accessibility permissions

// Get the accessibility element corresponding to the frontmost application.

AXUIElementRef appElem = AXUIElementCreateApplication(pid);

if (!appElem) {

return;

}

// Get the accessibility element corresponding to the frontmost window

// of the frontmost application.

AXUIElementRef window = NULL;

if (AXUIElementCopyAttributeValue(appElem,

kAXFocusedWindowAttribute, (CFTypeRef*)&window) != kAXErrorSuccess) {

CFRelease(appElem);

return;

}

// Finally, get the title of the frontmost window.

CFStringRef title = NULL;

AXError result = AXUIElementCopyAttributeValue(window, kAXTitleAttribute,

(CFTypeRef*)&title);

// At this point, we don't need window and appElem anymore.

CFRelease(window);

CFRelease(appElem);

if (result != kAXErrorSuccess) {

// Failed to get the window title.

return;

}

// Success! Now, do something with the title, e.g. copy it somewhere.

// Once we're done with the title, release it.

CFRelease(title);

可替代地，它可以是简单的使用CGWindow API，如在this StackOverflow answer提到。