UIImageView live filter being stretched over camera preview layer

Question

I am building a square camera that displays live filters. I have a UIView which displays the camera preview and I am adding a UIImage subview on top to overlay the filter. I have tried a variety of different settings but the UIImageView always ends up being the wrong aspect ratio.

Here is what I have

self.imageView = UIImageView(frame: view.bounds)
self.imageView.translatesAutoresizingMaskIntoConstraints = false
self.imageView.contentMode = UIViewContentMode.ScaleToFill
self.imageView.clipsToBounds = true
self.imageView.center = view.center
self.previewLayer!.frame = view.layer.bounds
view.clipsToBounds = true
view.layer.addSublayer(self.previewLayer!)
view.addSubview(self.imageView)

The UIView displaying the camera output is not stretched but the UIView I add as a subview ends up being stretched. A comparison of unfiltered VS filtered:

Answer 1

请尝试将contentMode更改为此：

self.imageView.contentMode = UIViewContentMode.ScaleAspectFit