On a view controller shown as part of a UINavigationController's stack, how do I tell if the Back button was pressed? The previously suggested answer from ages ago, to check isBeingDismissed(), seems to always return a false value.

In Apple's documentation it says this:"This method, though convenient, is inefficient if used multiple times in succession. Achieve better performance by chaining filters without asking for the outputs of individual filters."That confuses me though because I don't know how to link them together without getting the output. For example, this is my method to apply a TiltShift filter, based on the instructions from Apple's docs. When I perform the gradient filter, I have to take the outputImage of that to pass into the next filter. What's the right way to be doing this? override public var outputImage: CIImage? { guard let inputImage = inputImage else { return nil } let clamped = inputImage.clampedToExtent() let blurredImage = clamped.applyingGaussianBlur(sigma: inputRadius) var gradientParameters = [ "inputPoint0": CIVector(x: 0, y: 0.75 * inputImage.extent.height), "inputColor0": CIColor(red: 0, green: 1, blue: 0, alpha: 1), "inputPoint1": CIVector(x: 0, y: 0.5 * inputImage.extent.height), "inputColor1": CIColor(red: 0, green: 1, blue: 0, alpha: 0) ]; guard let gradientImage = ciImage(from: "CILinearGradient", parameters: gradientParameters) else { return nil } gradientParameters["inputPoint0"] = CIVector(x: 0, y: 0.25 * inputImage.extent.height) guard let backgroundGradientImage = ciImage(from: "CILinearGradient", parameters: gradientParameters) else { return nil } let maskParameters = [ kCIInputImageKey: gradientImage, kCIInputBackgroundImageKey: backgroundGradientImage ] guard let maskImage = ciImage(from: "CIAdditionCompositing", parameters: maskParameters) else { return nil } let combinedParameters = [ kCIInputImageKey: blurredImage, kCIInputBackgroundImageKey: clamped, kCIInputMaskImageKey: maskImage ] return ciImage(from: "CIBlendWithMask", parameters: combinedParameters) } private func ciImage(from filterName: String, parameters: [String: Any]) -> CIImage? { guard let filtered = CIFilter(name: filterName, parameters: parameters) else { return nil } return filtered.outputImage }

When I try to re-open the storyboard I was just editing in the current production version of Xcode it says"The document Main.storyboard could not be opened. The operation couldn't be completed. (com.apple.InterfaceBuilder error -1)"What in the world do I do to fix that? I *really* don't want to go back to my last git commit for that file because there have been quite extensive changes with pretty complex autolayout settings.