Ios16 on blog.iankulin.com

ImageRenderer()

Thu, 08 Dec 2022 00:00:00 +0000

ImageRenderer() is a SwiftUI class that creates an image from a view. You just initialize it with the view, then extract a cgImage (Core Graphics) or uiImage that can be cast to a SwiftUI Image.

I’ll need a view to work with, so here it is; a crude version of my behaviour ticket.

struct TicketView: View {
 var body: some View {
 ZStack {
 Color(.cyan)
 .frame(width: 300, height: 350)
 VStack {
 Text("Fred Bloggs")
 .font(.largeTitle)
 Text("")
 HStack {
 Text("Putting rubbish in the bin")
 Image(systemName: "trash")
 }
 .foregroundColor(.purple)
 Text("")
 Text("Green Faction")
 Text("")
 Text("")
 Text("\(Date().formatted())")
 }
 }
 }
}

Here it is, with a couple of buttons underneath:

I’ve assigned the view to a property of my content view, then displayed it along with the buttons. The first button saves the image to an @State and the second one displays it if it exists.

struct ContentView: View {
 private var ticketView = TicketView()
 @State private var image: Image?
 @State private var showImage = false
 
 var body: some View {
 VStack {
 Spacer()
 ticketView
 Spacer()

 Button("Save Image") {
 let renderer = ImageRenderer(content: ticketView)
 
 if let uiImage = renderer.uiImage {
 image = Image(uiImage: uiImage)
 }
 }.padding()
 
 Button("Toggle image") {
 withAnimation {
 showImage.toggle()
 }
 }
 if showImage {
 if let image = image {
 image
 .resizable()
 .scaledToFit()
 }
 }
 
 }
 .padding()
 }
}

If we save the screen:

Button("Save Image") {
 let renderer = ImageRenderer(content: ticketView)
 
 if let uiImage = renderer.uiImage {
 image = Image(uiImage: uiImage)
 }
}.padding()

Then it can just be inserted in the view same as any bitmap image by hitting the Toggle Image button.

SwiftUI provides

Wed, 07 Dec 2022 00:00:00 +0000

A few hours after I speculated about pausing work on the tickets app because outputting the tickets was too far out of my expertise, a helpful instance of the Baader–Meinhof phenomenon threw up some help in the form of this tweet from @FloWritesCode. It turns out this was an addition in iOS16 announced at WWDC that makes this straightforward.

As soon as I googled around about it I also found good solutions that wrapped the old code to provide similar functionality. So that’s a lesson for me about not assuming something’s hard before I’ve spent some time investigating it. I took that lesson and applied it to rendering to a PDF, and of course, @twostraws has a code example for that from three days ago!

Obviously I’m going to have some fiddling around to lay it out and so on, and I still need to figure out the share behaviour (which I’m expecting to be straightforward) but it feels like SwiftUI is just going to help me express my intents in code. I’m really enjoying this language, framework and community!

iOS 16 Developer Mode

Sat, 19 Nov 2022 00:00:00 +0000

I updated my iPhone to iOS16 this morning, and tonight when I went to run one of my apps, it complained that it needed Developer mode. This is a new, probably wise, way to avoid dodgy apps being loaded on a phone. I don’t know exactly how you’d do that, but then I’m not a black hatted cyber terrorist.

I had to google the setting, it’s in “Privacy and Security” down the bottom, and requires a reboot. When you open the phone there’s another dialog and you need to reauth.