# performClose(_:) Simulates the user clicking the close button by momentarily highlighting the button and then closing the window. ``` func performClose(_ sender: Any?) ``` ## Parameters `sender` The message’s sender. ## Discussion If the window’s delegate or the window itself implements [`windowShouldClose(_:)`](/documentation/AppKit/NSWindowDelegate/windowShouldClose(_:)), the window sends that message with the window as the argument. The window sends only one such message; if both the delegate and the window implement the method, the delegate receives the message. If the [`windowShouldClose(_:)`](/documentation/AppKit/NSWindowDelegate/windowShouldClose(_:)) method returns , the window doesn’t close. If neither the window nor the delegate implement [`windowShouldClose(_:)`](/documentation/AppKit/NSWindowDelegate/windowShouldClose(_:)), or it returns , this method invokes [`close()`](/documentation/AppKit/NSWindow/close()) to close the window. If the window doesn’t have a close button or can’t close (for example, if the delegate replies to a [`windowShouldClose(_:)`](/documentation/AppKit/NSWindowDelegate/windowShouldClose(_:)) message), the system emits the alert sound. ## See Also [`styleMask`](/documentation/AppKit/NSWindow/styleMask-swift.property) Flags that describe the window’s current style, such as if it’s resizable or in full-screen mode. [`- performMiniaturize:`](/documentation/AppKit/NSWindow/performMiniaturize(_:)) Simulates the user clicking the minimize button by momentarily highlighting the button, then minimizing the window. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)