How can i wait for 2 seperate UIGraphicsImageRenderer tasks to complete

2022-01-25 13:52 Halpo imported from Stackoverflow

I have 2 UIGraphicsImageRenderer tasks with different renderers and when i run this, only one task is returned as it is synchronous, how do I wait until both have created images before returning them?

func createShareImage(callback: @escaping (_ image: UIImage, _ bgImage: UIImage) -> Void) {

    let canvas = UIView()
    ...

    let format = UIGraphicsImageRendererFormat()
    format.scale = UIScreen.main.scale

    let renderer = UIGraphicsImageRenderer(size: canvas.bounds.size, format: format)
    let stickerImage = renderer.image { _ in
        canvas.drawHierarchy(in: canvas.bounds, afterScreenUpdates: true)
    }

    let bgImageView = UIView()
    ...

    let bgRenderer = UIGraphicsImageRenderer(size: bgImageView.bounds.size, format: format)
    let bgImage = bgRenderer.image { _ in
        bgImageView.drawHierarchy(in: bgImageView.bounds, afterScreenUpdates: true)
    }

    callback(stickerImage, bgImage)
    
}

1 answer

answered 2022-01-25 14:17 Sh_Khan

Testing your code

func createShareImage(callback: @escaping (_ image: UIImage, _ bgImage: UIImage) -> Void) {

    let canvas = UIView(frame: CGRect.init(x: 0, y: 0, width: 200, height: 200))
    canvas.backgroundColor = .red
    let format = UIGraphicsImageRendererFormat()
    format.scale = UIScreen.main.scale
    print("1:",Thread.isMainThread)
    let renderer = UIGraphicsImageRenderer(size: canvas.bounds.size, format: format)
    let stickerImage = renderer.image { _ in
        canvas.drawHierarchy(in: canvas.bounds, afterScreenUpdates: true)
        print("2:",Thread.isMainThread)
    }

    let bgImageView = UIView(frame: CGRect.init(x: 0, y: 0, width: 2000, height: 2000))
    bgImageView.backgroundColor = .green
    let bgRenderer = UIGraphicsImageRenderer(size: bgImageView.bounds.size, format: format)
    let bgImage = bgRenderer.image { _ in
        bgImageView.drawHierarchy(in: bgImageView.bounds, afterScreenUpdates: true)
        print("3:",Thread.isMainThread)
    }

    print("4:",Thread.isMainThread)
    callback(stickerImage, bgImage)
}

Gets

1: true
2: true
3: true
4: true

Which means there is no async part , all the code is synchronous and serial and no waiting need to happen

See also questions close to this topic

Command failed: xcrun instruments -s

I want to run my react native app on a real ios device with this line :

npx react-native run-ios --udid SOME-UDID

but i got this error :

xcrun: error: sh -c '/Applications/Xcode.app/Contents/Developer/usr/bin/xcodebuild -sdk /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk -find instruments 2> /dev/null' failed with exit code 17664: (null) (errno=No such file or directory)
xcrun: error: unable to find utility "instruments", not a developer tool or in PATH
error Command failed: xcrun instruments -s
xcrun: error: sh -c '/Applications/Xcode.app/Contents/Developer/usr/bin/xcodebuild -sdk /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk -find instruments 2> /dev/null' failed with exit code 17664: (null) (errno=No such file or directory)
xcrun: error: unable to find utility "instruments", not a developer tool or in PATH

everything is ok on simulator

I'm using XCODE 13

IOS Launcher in android studio

I'm trying to change the whole Android OS installed app icons into IOS icons, please help me with the proper code or library for android kotlin

Debugging undefined is not an object (evaluating 'Object.keys(routeConfigs)')

I'm using Expo and React Native to create a simple iOS app. I am currently getting this error and have no idea how to fix it. I've tried various other solutions on Stack Overflow to no avail.

My code is:

import 'react-native-gesture-handler';
import React from 'react';
import { createStackNavigator } from 'react-navigation-stack';
import { NavigationContainer } from '@react-navigation/native';
import HomeScreen from './src/screens/HomeScreen';

const Stack = createStackNavigator();

export default function App() {
  return (
    <NavigationContainer>
    <Stack.Navigator>
      <Stack.Screen name="Home" component={HomeScreen} />
    </Stack.Navigator>
    </NavigationContainer>
  );
}

Here is my HomeScreen.js

import React from 'react';
import { Text, View } from 'react-native';

export default function HomeScreen () {
  return (
    <View>
      <Text>Welcome Home!</Text>
    </View>
  )
}

My packages:

  "packages": {
    "": {
      "name": "safey",
      "version": "1.0.0",
      "dependencies": {
        "@react-native-community/masked-view": "^0.1.11",
        "@react-navigation/native": "^6.0.10",
        "@react-navigation/stack": "^6.0.10",
        "expo": "~45.0.0",
        "expo-splash-screen": "~0.15.1",
        "expo-status-bar": "~1.3.0",
        "react": "17.0.2",
        "react-dom": "17.0.2",
        "react-native": "0.68.1",
        "react-native-gesture-handler": "^2.4.2",
        "react-native-reanimated": "^2.8.0",
        "react-native-safe-area-context": "^4.2.5",
        "react-native-screens": "^3.13.1",
        "react-native-web": "0.17.7",
        "react-navigation": "^4.4.4",
        "react-navigation-stack": "^2.10.4"
      },

SwiftUI, apply drawGesture only when over Image

I'm try to apply the gesture only when the user is over the Image display not when tapped outside the image.

Any suggestion how I can do? this following code draw also when user tap outside the image.

struct ContentView: View {
    @StateObject var am = AppManager()
    @State var switchToTakePicture = false
    @State var paths: [PathContainer] = []
    @State var currentDraggingId = UUID()
    @State var spikoPic = #imageLiteral(resourceName: "spiko-16.jpeg")
    @State var centerOFimage = CGSize(width: 0, height: 0)
    var body: some View {
        
        GeometryReader { proxy in
            ZStack {
                Image(uiImage: spikoPic)
                    .resizable()
                    .scaledToFit()
                    .position(x: proxy.size.width/2, y: proxy.size.height/2)
                    .background(GeometryReader {
                        Color.clear.preference(key: ViewRectKey.self,
                                               value: [$0.frame(in: .global)])
                    })
                    .gesture(drawGesture) // not correct
                
                ForEach(paths) { container in
                    // draw and set the foreground color of the paths to red
                    container.path
                        .stroke(Color.red, lineWidth: 4)
                    
                    
                }
            }
            .onPreferenceChange(ViewRectKey.self) { rects in
                print(rects.first ?? .zero)
                
            }
        }
        
    }
    var drawGesture: some Gesture {
        
        DragGesture(minimumDistance: 0)
            .onChanged { value in
                
                // The point that the gesture started from
                let start = value.startLocation
                // The point that the gesture ended to
                let end = value.location
                // the properties of the rectangle to be drawn
                let rectangle: CGRect = .init(origin: end,
                                              size: .init(width: start.x - end.x,
                                                          height: start.y - end.y))
                // create a path for the rectangle
                let path: Path = .init { path in
                    
                    path.addRect(rectangle)
                }
                
                print("rettangolo = \(rectangle) orig \(rectangle.origin) - height \(rectangle.height) width = \(rectangle.width)")
                
                // remove the previous rectangle that was drawen in current
                // process of drawing
                paths.removeAll { $0.id == currentDraggingId }
                // append the new rectangle
                paths.append(.init(id: currentDraggingId, path: path))
            }
            .onEnded { _ in
                // renew the dragging id so the app know that the next
                // drag gesture is drawing a completely new rectangle,
                // and is not continuing the drawing of the last rectangle
                currentDraggingId = .init()
            }
    }
}

i want no box outside

How to navigate between NavigationLink while leave a part of main window stay the same in SwiftUI
I would like to navigate between different NavigationLinks in NavigationView while some part of the main window stay the same. For example, I want to make a music app and I want to let the play controller always on top, while I can display different navigation contents (songs page, artists page...) using the rest of the window.

Like what's showed in the picture below, I want to keep the red part always there while the blue part changes.

Navigation Example Picture

My code would be like below, but it won't work correctly. The AlwaysStayView() disappears when I click any NavigationLink on sidebar. So, how can I correct it or is there any solution (prefer in SwiftUI, but framework like UIKit would also be OK). I would appreciate it.
```
NavigationView {
            List {
                NavigationLink { DiscoverView() }
                    label: { Label("Discover", systemImage: "magnifyingglass") }
                NavigationLink { SongsView() }
                    label: { Label("Songs", systemImage: "music.note") }
                NavigationLink { ArtistsView() }
                    label: { Label("Artists", systemImage: "music.mic") }
                }
            }
            .listStyle(SidebarListStyle())

            VStack {
                AlwaysStayView()
                SongsView()
            }
}
```

NumberFormatter and unsigned with UInt64.max

I'm trying to create a string representing UInt64.max using NumberFormatter. Here's the code:

let formatter = NumberFormatter()
    
formatter.usesGroupingSeparator = true
formatter.numberStyle = .decimal
formatter.positiveFormat = "# ##0.#########"
formatter.maximumSignificantDigits = 20
formatter.usesSignificantDigits = false
formatter.maximumFractionDigits = 20
formatter.minimumFractionDigits = 0
formatter.alwaysShowsDecimalSeparator = false
// formatter.roundingMode = .halfUp
let text1 = formatter.string(for: NSNumber(value: Int64.max))
let text2 = formatter.string(for: NSNumber(value: UInt64.max))

print(text1)
print(text2)

which prints:

Optional("9,223,372,036,854,780,000")
Optional("-1")

but should print

Optional("9223372036854775807")
Optional("18,446,744,073,709,551,615")

It looks like NSNumber is rounding Int64 and isn't taking the UIn64. The obj-c version of NSNumberFormatter works fine.

Am I missing something or is there a problem with NumberFormatter?

SwiftUI technique to update UINavigationBarAppearance.backgroundImage dynamically?

I am implementing a gradient background for the top navigation bar in SwiftUI using a standard NavigationView. For the gradient I am using a UIGraphicsImageRenderer to create a gradient image which I then assign to the backgroundImage of UINavigationBarAppearance. So far everything is behaving correctly in terms of drawing the gradient and having it render on the top bar.

However, I have not yet been able to make the backgroundImage change dynamically per view. Full code below that should work if you paste it into a playground.

import SwiftUI

struct NavBarGradient: ViewModifier {
    
    init(from: UIColor, to: UIColor) {
        let appearance = UINavigationBarAppearance()
        appearance.backgroundColor = .clear
        
        let imageRenderer = UIGraphicsImageRenderer(size: .init(width: 1, height: 1))
        let gradientImage : UIImage = imageRenderer.image { ctx in
            let gradientLayer = CAGradientLayer()
            gradientLayer.frame = imageRenderer.format.bounds
            gradientLayer.colors = [from.cgColor, to.cgColor]
            gradientLayer.locations = [0, 1]
            gradientLayer.startPoint = .init(x: 0.0, y: 0.0)
            gradientLayer.endPoint = .init(x: 0.5, y: 1.0)
            
            gradientLayer.render(in: ctx.cgContext)
        }
        appearance.backgroundImage = gradientImage
        
        UINavigationBar.appearance().standardAppearance = appearance
        UINavigationBar.appearance().compactAppearance = appearance
        UINavigationBar.appearance().scrollEdgeAppearance = appearance
    }
    
    func body(content: Content) -> some View {
        content
    }
    
}

extension View {
    func navBarGradient(from: UIColor = .systemRed, to: UIColor = .systemYellow) -> some View {
        modifier(NavBarGradient(from: from, to: to))
    }
}

struct SimpleView: View {
    var body: some View {
        Text("Gradient View").navigationTitle("Gradient Colors")
    }
}

struct ContentView: View {
    var body: some View {
        NavigationView {
            List {
                NavigationLink(
                    "Blue to Cyan",
                    destination: SimpleView()
                        .navBarGradient(from: .systemBlue, to: .systemCyan)
                )
                NavigationLink(
                    "Green to Mint",
                    destination: SimpleView()
                        .navBarGradient(from: .systemGreen, to: .systemMint)
                )
                NavigationLink(
                    "Red to Yellow",
                    destination: SimpleView()
                        .navBarGradient() // comment me out and previous modifier wins
                )
            }
                .navigationTitle("Main Menu")
                .navigationBarTitleDisplayMode(.inline)
        }
    }
}

Right now the .navBarGradient() view modifier seems to be "last one wins" which makes sense given how the view system works in SwiftUI. So what I am trying to understand is - what is the "SwiftUI way" of updating the appearance dynamically?

I have been able to achieve a gradient background in the top bar by adapting solutions like this one; it works exactly as desired. But it seems that it would be a useful thing to be able to update the top bar background image dynamically for things like server-side images.

Thanks in advance!

Weird error when trying to take a snapshot of a uiview using UIGraphicsImageRenderer
I'm getting the following error when I call this extension:
```
extension UIView {
    
    /// Create image snapshot of view.
    func snapshot(of rect: CGRect? = nil) -> UIImage {
        return UIGraphicsImageRenderer(bounds: rect ?? bounds).image { _ in
            drawHierarchy(in: bounds, afterScreenUpdates: true)
        }
    }
}
```
The error:

vImageConvert_AnyToAny - failed width = 0 height = 1 dst component = 16bit float dstLayout = ByteOrder16Little dstBytesPerRow = 0 src component = 16bit integer srcLayout = ByteOrder16Little srcBytesPerRow = 0

Any ideas why this would be the case? Wondering if a color space issue... works fine on simulator, breaks on physical device.

Related questions

How can i wait for 2 seperate UIGraphicsImageRenderer tasks to complete

1 answer

See also questions close to this topic