NSApplicationDelegate在从ShouldTerminate返回NSTerminater后没有收到延迟呼叫?

我在Xcode中创建了一个Mac应用程序。我所做的唯一代码更改是在app delegate中。现在,它的整体内容如下:

#import "AppDelegate.h"

@interface AppDelegate ()

@end

@implementation AppDelegate

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
}

- (void) readyToTerminate: (id) sender {
  NSLog(@"Ready to terminate");
  [NSApplication.sharedApplication replyToApplicationShouldTerminate:YES];
}

- (NSApplicationTerminateReply) applicationShouldTerminate:(NSApplication *)sender {
  [self performSelector:@selector(readyToTerminate:) withObject:self afterDelay:1.0];
  NSLog(@"Later please");
  return NSTerminateLater;
}

- (void)applicationWillTerminate:(NSNotification *)aNotification {
  NSLog(@"Terminating");
}

@end

当我运行应用程序时,我确实看到了一个窗口。然后我点击command-Q终止。输出为:

2018-04-01 17:20:03.110563-0500 TerminateThisApp[3336:364401] Unknown Window 
class (null) in Interface Builder file,
     creating generic Window instead
2018-04-01 17:20:06.929175-0500 TerminateThisApp[3336:364401] Later please

所以readyToTerminate:没有被调用。为什么会这样?我不明白。

不管它值多少钱,我尝试了一个NSTimer,但没有得到同样的结果。我还试着用同样的方式从didFinishLaunching调用readyToTerminate。在这种情况下,readyToTerminate确实启动了(应用程序没有终止,这很好)。

发生了什么事?