CIFilter输出图像为零 [英] CIFilter output image nil

问题描述

我正在使用核心图像，我正在为我的图像应用CIFilter棕褐色调。我在viewDidLoad中运行一次过滤器，然后立即调用另一个再次添加过滤器的函数。出于某种原因，当我尝试访问输出图像时，应用程序崩溃并说输出图像为零。有人知道为什么会这样吗？

I am using core image and I am applying a CIFilter sepia tone to my image. I run a filter once in viewDidLoad and then immediately call another function that adds the filter again. For some reason, when I try to access the output image, the app crashes and says the output image is nil. Anyone know why this is happening?

谢谢

    import UIKit

class ViewController: UIViewController {
    @IBOutlet weak var myimage: UIImageView!

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        let image = CIImage(image: myimage.image)
        let filter = CIFilter(name: "CISepiaTone")
        filter.setDefaults()
        filter.setValue(image, forKey: kCIInputImageKey)
        myimage.image = UIImage(CIImage: filter.outputImage)
        self.reapplyFilter()
    }

        func reapplyFilter(){
            let image = CIImage(image: myimage.image)
            let filter = CIFilter(name: "CISepiaTone")
            filter.setDefaults()
            filter.setVa    lue(image, forKey: kCIInputImageKey)
    //ERROR HERE: fatal error: unexpectedly found nil while unwrapping an Optional value
            myimage.image = UIImage(CIImage: filter.outputImage)
//ERROR
        }

        override func didReceiveMemoryWarning() {
            super.didReceiveMemoryWarning()
            // Dispose of any resources that can be recreated.
        }



}

推荐答案

你不能调用 UIImage（CIImage：）并使用该UIImage作为UIImageView的图像。 UIImageView需要一个由位图（CGImage）支持的UIImage。用CIImage实例化的UIImage没有位图;它没有实际图像，它只是一组应用过滤器的指令。这就是你的UIImageView图像为零的原因。

You cannot call UIImage(CIImage:) and use that UIImage as the image of a UIImageView. UIImageView requires a UIImage backed by a bitmap (CGImage). A UIImage instantiated with CIImage has no bitmap; it has no actual image, it's just a set of instructions for applying a filter. That is why your UIImageView's image is nil.

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