iOS获取window

(UIWindow *)lastWindow { NSEnumerator *frontToBackWindows = [UIApplication.sharedApplication.windows reverseObjectEnumerator]; for (UIWindow *window in frontToBackWindows) { BOOL windowOnMainScreen = window.screen == UIScreen.mainScreen; BOOL windowIsVisible = !window.hidden && window.alpha > 0; BOOL windowLevelSupported = (window.windowLevel >= UIWindowLevelNormal && window.windowLevel <= UIWindowLevelNormal); BOOL windowKeyWindow = window.isKeyWindow;

  if(windowOnMainScreen && windowIsVisible && windowLevelSupported && windowKeyWindow) {
      return window;
  }

}

return nil; }