How can I crop a UIImage for SwiftUI on iOS for free?

Cropping a UIImage for use in SwiftUI on iOS can be done efficiently without any third-party libraries. You can leverage CGImage functions to accomplish this. Here's how you can do it for free:

1. Create a Cropping Function:

First, we'll define an extension to the UIImage class which has a crop method:

extension UIImage {
  func cropped(to rect: CGRect) -> UIImage? {
 guard let cgImage = self.cgImage?.cropping(to: rect) else {
   return nil
 }   return UIImage(cgImage: cgImage)
 }
}


This method checks if it can make CGImage, crops the image, then re-creates it as UIImage. If cropping fails it return null

2. Usage in SwiftUI:

You can now use the `cropped(to:)` function in SwiftUI. For instance, let's assume that we are cropping a square UIImage in a simple view. Note that, you'd typically handle the original image in different context where you store the UIImage, in this case we create one just as a demo:

struct ContentView: View {
  let originalImage: UIImage = UIImage(named: "your_image") ?? UIImage() // your image here
  var body: some View {
  if let croppedImage = originalImage.cropped(to: CGRect(x: 20, y: 20, width: 100, height: 100)) {
    Image(uiImage: croppedImage) //shows the cropped image
  } else {
   Text("Image could not be cropped")
  }
  }
}

This code gets a UIImage called 'your_image' or creates an empty one if something fails. It then creates a 100x100 pixel box offsetted by x=20, y=20. Finally it shows a Image with the croppedImage variable, otherwise if something went wrong during the process we display "Image could not be cropped"

Important Notes:

- Always make sure to handle cases where self.cgImage is nil to prevent the program from crashing.

- Remember that coordinates for cropping are defined using `CGRect`, so if for instance we are talking about coordinate systems, it begins in the upper left part of the image.

- You may have to adjust your image's size for a correct behaviour based on your desired effect in your `View` code.

This approach is efficient and doesn't require third-party frameworks, making it a free and reliable option for cropping images in SwiftUI.

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