Supporting SwiftUI with Core Graphics
Heads up... You’re accessing parts of this content for free, with some sections shown as text.
Heads up... You’re accessing parts of this content for free, with some sections shown as text.
Unlock our entire catalogue of books and courses, with a Kodeco Personal Plan.
Unlock now
We’ve got one important piece missing from our drawing pad implementation. We aren’t storing our drawings, and we can’t see a thumbnail version in the mindmap cell. We’ll fix that up in this episode, with some more help from UIGraphicsImageRenderer.
Model.swift
We’ll start with updating the cell’s model, in CellModel.swift
var drawing: 🟩UIImage?
mutating func update(drawing: 🟩UIImage) {
self.drawing = drawing
}
func updateDrawing(cell: Cell, drawing: 🟩UIImage) {
CellView.swift
We’ll need to update the actual cell view, as well.
Down in the body, find the if statement checking for a drawing.
And replace this drawing view, with an Image made from our drawing UIImage.
Image(uiImage: drawing)
DrawingPadView.swift
Back in DrawingPadView.swift, we can uncomment the code in the save button, and because we updated the underlying types and CellStore method, this will just work!
if let cell = cellStore.selectedCell,
let drawing = drawing {
cellStore.updateDrawing(cell: cell, drawing: drawing)
}
ContentView.swift
One more thing, in ContentView.swift, we need to pass the selected cell’s drawing into the drawing pad again.
DrawingPadView(drawing: cellStore.selectedCell?.drawing)
Model.swift
We’ll start in the model, again. Create a new computed property on Cell for the thumbnail. We’ll return an Image that we’ll create from the resized UIImage. Make sure that there is a drawing image. If there isn’t then just return nil.
var thumbnail: Image? {
guard let drawing = self.drawing else {
return nil
}
}
let thumbnailSize = CGSize(width: drawing.size.width / 6,
height: drawing.size.height / 6)
let thumbnail = UIGraphicsImageRenderer(size: thumbnailSize).image { context in
}
return Image(uiImage: thumbnail)
drawing.draw(in: CGRect(origin: .zero, size: thumbnailSize))
CellView.swift
So back in CellView.swift. Just under CellView, open a new extension. Create a new View structure for the Cell thumbnail. Give it size and image properties to define the thumbnail.
extension CellView {
struct Thumbnail: View {
let size: CGSize
let drawing: Image
var body: some View {
}
}
}
ZStack {
Color(uiColor: .systemBackground)
drawing
.resizable()
.aspectRatio(contentMode: .fit)
.frame(width: size.width, height: size.height)
}
Thumbnail(size: cell.size, drawing: Image(uiImage: drawing))
.clipShape(cell.shape.shape)