ViewModifier for resizing images in SwiftUI. Resize an image to any size (square, circle, rectangle) while maintaining its aspect ratio.

swiftui-resize-image-and-maintain-aspect-ratio.swift

import SwiftUI

/// Common aspect ratios
public enum AspectRatio: CGFloat {
    case square = 1
    case threeToFour = 0.75
    case fourToThree = 1.75
}

/// Fit an image to a certain aspect ratio while maintaining its aspect ratio
public struct FitToAspectRatio: ViewModifier {
    
    private let aspectRatio: CGFloat
    
    public init(_ aspectRatio: CGFloat) {
        self.aspectRatio = aspectRatio
    }
    
    public init(_ aspectRatio: AspectRatio) {
        self.aspectRatio = aspectRatio.rawValue
    }
    
    public func body(content: Content) -> some View {
        ZStack {
            Rectangle()
                .fill(Color(.clear))
                .aspectRatio(aspectRatio, contentMode: .fit)

            content
                .scaledToFill()
                .layoutPriority(-1)
        }
        .clipped()
    }
}

// Image extension that composes with the `.resizable()` modifier
public extension Image {
    func fitToAspectRatio(_ aspectRatio: CGFloat) -> some View {
        self.resizable().modifier(FitToAspectRatio(aspectRatio))
    }
    
    func fitToAspectRatio(_ aspectRatio: AspectRatio) -> some View {
        self.resizable().modifier(FitToAspectRatio(aspectRatio))
    }
}

I can’t stress the importance of solving this problem enough when you have images and thumbnails all over the place. Resizing really sucks even now in SwiftUI and it shouldn’t be this complex. Whatever this article does to solve it should ideally become part of SwiftUI's default. Seriously!!
I’m yet to meet someone who says they don't want to have aspect ratio maintained while resizing images and therefore this must be the default and not the crap that SwiftUI currently offers. It’s pathetic! I This is absolutely critical and will save so much time. Please see if you can suggest it as a language / framework feature.