可选类型“UIImage?"的值没有打开 [英] Value of optional type 'UIImage?' not unwrapped

问题描述

我正在尝试创建一个简单的过滤器应用程序，用于在按下按钮时过滤显示的图像.

I'm trying to create a simple filter app that filters the displayed image upon a button press.

 @IBAction func applyFilter(sender: AnyObject) {

    // Create an image to filter
    let inputImage = CIImage(image: photoImageView.image)

    // Create a random color to pass to a filter
    let randomColor = [kCIInputAngleKey: (Double(arc4random_uniform(314)) / 100)]

    // Apply a filter to the image
    let filteredImage = inputImage.imageByApplyingFilter("CIHueAdjust", withInputParameters: randomColor)

    // Render the filtered image
    let renderedImage = context.createCGImage(filteredImage, fromRect: filteredImage.extent())

    // Reflect the change back in the interface
    photoImageView.image = UIImage(CGImage: renderedImage)

}

我不断收到错误:

可选类型UIImage?"的值未拆封.

Value of optional type 'UIImage?' not unwrapped.

我在这里做错了什么?我是 Swift 初学者.

What am I doing wrong here? I'm a Swift beginner.

推荐答案

UIImageView 的图像属性中并不总是包含 UIImage.

An UIImageView does not always have an UIImage in its image property.

你应该先检查一下:

guard let img = photoImageView.image else { return }
let inputImage = CIImage(image: img)

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