I've been wondering if there is any way to customize the preview image of the view that's being dragged when using onDrag?
As you might see, the preview image is by default a slightly bigger opacity image of the view.
From what I have found, a preview image is generated at the very beginning of the dragging process. But I couldn't find a way to change it.
What I mean by customizing is to have some custom image or a preview image of a custom view. (Both without the default opacity)
Does anyone have an idea?
I have tried to use previewImageHandler and in general, read a lot about the NSItemProvider. But for me, it seems like this is something that is not possible for SwiftUI yet?
With UIKit one could have just customized the UIDragItem - something like that using previewProvider: Here
Here is my demo code:
struct ContentView: View {
var body: some View {
DraggedView()
.onDrag({ NSItemProvider() })
}
private struct DraggedView: View {
var body: some View {
RoundedRectangle(cornerRadius: 20)
.frame(width: 120, height: 160)
.foregroundColor(.green)
}
}
}
I will use this for drag and drop within a LazyVGrid, so custom gestures are unfortunately no option.
One second idea I had would be to have a gesture simultaneously that first changes the item to be dragged to something else and then onDrag starts and returns the NSItemProvider with the preview image which would be then the one I would want. But I couldn't have those two gestures go at the same time, you would have to dismiss one first in order to start the second.
Thank you!
iOS 15 adds an API to do this - you can specify the View to use for the preview. onDrag(_:preview:)
RoundedRectangle(cornerRadius: 20)
.frame(width: 120, height: 160)
.foregroundColor(.green)
.onDrag {
NSItemProvider()
} preview: {
RoundedRectangle(cornerRadius: 18)
.frame(width: 100, height: 140)
.foregroundColor(.green)
}
Related
Consider the following example:
struct ContentView: View {
#State var showSplash: Bool = true
#Namespace var animationNamespace
var body: some View {
ZStack {
if showSplash {
GeometryReader { geometry in
AsyncImage(url: URL(string: "https://picsum.photos/seed/864a5875-6d8b-43d6-8d65-04c5cfb13f3b/1920/1440")) { image in
image.resizable()
.scaledToFill()
.matchedGeometryEffect(id: "SplashImage", in: animationNamespace)
.transition(.move(edge: .bottom))
.frame(width: geometry.size.width)
.transition(.move(edge: .bottom))
.edgesIgnoringSafeArea(.all)
.clipped()
} placeholder: {
Color.gray
}
}
.onTapGesture {
toggleSplashScreen(false)
}
} else {
ScrollView {
GeometryReader { geometry in
AsyncImage(url: URL(string: "https://picsum.photos/seed/864a5875-6d8b-43d6-8d65-04c5cfb13f3b/1920/1440")) { image in
image
image
.resizable()
.scaledToFill()
.matchedGeometryEffect(id: "SplashImage", in: animationNamespace)
.transition(.move(edge: .bottom))
} placeholder: {
Color.gray
}
.frame(width: geometry.size.width, height: 400)
.clipped()
}
.edgesIgnoringSafeArea(.all)
.onTapGesture {
toggleSplashScreen(true)
}
}
}
}
}
}
With a helper method here:
private extension ContentView {
func toggleSplashScreen(_ toggle: Bool) {
withAnimation(.spring(response: 0.85, dampingFraction: 0.95)) {
showSplash = toggle
}
}
}
This produces:
I noticed two things here that I would like to fix
The flashing white effect when transitioning between the two states.
I noticed since we are using AsyncImage, when showSplash changes the AsyncImages only sometimes hits the placeholder block. As a result, the transition becomes really choppy. I tested this with a static image from the assets file and the transition then became smooth. I also tried creating a Caching mechanism on the AsyncImage but still had issues with it hitting placeholder block sometimes.
Would love to hear any ideas :) Thanks!
There are a couple of things that I think you could do to improve this.
First, You are fighting a little bit against the way SwiftUI maintains a view's identity. One of the ways that SwiftUI determines when it can reuse an existing structure as opposed to recreating a structure, is by it's location in the view hierarchy. So when you toggle your structure you go from:
GeometryReader
AsyncImage
to
ScrollView
GeometryReader
AsyncImage
As a result, the system thinks these are two AsyncImage views and so it's rebuilding the view (and reloading the image) every time. I think that's where your white flashes come from since you're seeing your gray placeholder in the middle of your animation. If you could leave the scroll view in place, possibly disabling scrolling when it's not needed (if that's possible) then the OS could maintain the identity of the AsyncImage. (see https://developer.apple.com/videos/play/wwdc2021/10022/)
That leads to the second area of investigation for you. AsyncImage is wonderful in the convenience it gives you in loading content from the network. Unfortunately it doesn't make that communication faster. Your goal should be to have AsyncImage go to the network as few times as possible.
Right now, your resizing strategy focuses on resizing the image. That means that for every transition you're "hitting the network" (read putting your code on the slow, dusty, dirt road path). Instead of resizing the image, you should just load the image once (the slow part) and resize the view that is displaying it. The general idea would be to let AsyncImage load the image, then control how the image is animated by animating the frame of the view.
This is where I get less helpful. I don't know enough about AsyncImage to know if it's capable of implementing that strategy. It seems that it should be... but I don't know that it is. You might have to resort to downloading and storing the image as state separately from the view that presents it.
So my advice is to limit the number of times AsyncImage has to reload the network data. That involves helping SwiftUI maintain the identity of the AsyncImage so it doesn't have to reload each time the view is created. And, try to implement your animations and scaling on the view, not the image, because rescaling the image also requires a network reload.
I have in my app a layout showing a list of rectangular cards - each one should be tappable (once) to reveal a set of action buttons and more information, etc.
I have implemented this using .onTapGesture() and I have also put .contentShape(Rectangle() to enforce the tappable area. However, while my implementation works fine for touchscreen interface, when I'm using it with the iPadOS mouse support, and on Catalyst for that matter, I see some very unexpected behaviour.
I've made a minimal reproducible example below that you can copy to recreate the problem.
Where the problems are when using mouse/trackpad input:
Not every click of the mouse is recorded as a tap gesture. This is happening mostly arbitrary except from in a few cases:
It seems to click either only in very specific areas, or when clicking multiple times in the same spot.
It seems that in a lot of cases only every other click is recorded. So I double click to get only one tap gesture.
It isn't evident in this example code, but in my main app the tappable areas are seemingly arbitrary - you can usually click near text or in alignment with it to record a tap gesture, but not always.
If you are running the example code you should be able to see the problem by repeatedly moving the mouse and attempting one click. It doesn't work unless you click multiple times in the same spot.
What does work as expected:
All input using touch instead of mouse; regardless of where you tap it records a tap gesture.
Mouse input when running as a native Mac target. The issues mentioned above are only for mouse/trackpad when running the example under iPadOS and Mac Catalyst.
Code I used to recreate this problem (has a counter to count every time a tap gesture is recorded):
struct WidgetCompactTaskItemView: View {
let title: String
let description: String
var body: some View {
HStack {
Rectangle()
.fill(Color.purple)
.frame(maxWidth: 14, maxHeight: .infinity)
VStack(alignment: .leading) {
Text(title).font(.system(size: 14, weight: .bold, design: .rounded))
Text(description).font(.system(.footnote, design: .rounded))
.frame(maxHeight: .infinity)
.fixedSize(horizontal: false, vertical: true)
.lineLimit(1)
.padding(.vertical, 0.1)
Spacer()
}
.padding(.horizontal, 6)
.padding(.top, 12)
}
.frame(maxWidth: .infinity, maxHeight: 100, alignment: .leading)
.background(Color.black)
.cornerRadius(16)
.overlay(
RoundedRectangle(cornerRadius: 16)
.stroke(Color.green, lineWidth: 0.5)
)
}
}
struct ContentView: View {
#State var tapCounter = 0
var body: some View {
VStack {
Text("Button tapped \(tapCounter) times.")
WidgetCompactTaskItemView(title: "Example", description: "Description")
.contentShape(Rectangle())
.onTapGesture(count: 1) {
tapCounter += 1
}
Spacer()
}
}
}
I have tried several things including moving modifiers around, setting eoFill to true on the contentShape modifier (which didn't fix the problem but simply made different unexpected behaviour).
Any help to find a solution that works as expected and works consistently whether mouse or touch would be much appreciated. I am not sure if I am doing something wrong or if there is a bug here, so please try and recreate this example yourself using the code to see if you can reproduce the problem.
So I realised that there was a much better solution that could bypass all the oddities that .onTapGesture had for me with mouse input. It was to encapsulate the whole view in a Button instead.
I made this into a modifier similar to onTapGesture so that it's much more practical.
import Foundation
import SwiftUI
public struct UltraPlainButtonStyle: ButtonStyle {
public func makeBody(configuration: Self.Configuration) -> some View {
configuration.label
}
}
struct Tappable: ViewModifier {
let action: () -> ()
func body(content: Content) -> some View {
Button(action: self.action) {
content
}
.buttonStyle(UltraPlainButtonStyle())
}
}
extension View {
func tappable(do action: #escaping () -> ()) -> some View {
self.modifier(Tappable(action: action))
}
}
Going through this:
I first have a button style which simply returns the label as is. This is necessary because the default PlainButtonStyle() still has a visible effect when clicked.
I then create a modifier that encapsulates the content given in a Button with this button style, then add that as an extension to View.
Usage example
WidgetCompactTaskItemView(title: "Example", description: "Description")
.tappable {
tapCounter += 1
}
This has solved all problems I've been having with clickable area using a mouse.
I noticed that a Text with .italic() clips letters:
Setting frame size doesn't help:
.paddings() doesn't help either. kerning(5) I don't want to use as it fixes the problem partially, at the right edge only, but it adds unwanted letter spacing.
struct ItalicTest: View {
var body: some View {
Text("F")
.font(Font.system(size: 60))
.italic()
.fontWeight(.black)
.frame(width: 60, height: 60)
.background(Color.red)
}
}
I'd like to prevent clipping. Do you know a solution using pure SwiftUI?
I know this is an old question, but I just had the same issue and found a propper solution.
You will have to add padding to your text and ask swiftui to collapse the padding and text before rendering it.
struct ItalicTest: View {
var body: some View {
Text("F")
.font(Font.system(size: 60))
.italic()
.fontWeight(.black)
.padding(.horizontal) // <-- add padding
.drawingGroup() // collapse the view and render together
}
}
When you use a SwiftUI Form it creates padding on the leading edge, which is fine for Form input but I would like to add additional content to the Form e.g. an image that takes the entire width of the screen, but because the image is in the Form, padding gets applied and the image gets pushed off screen slightly. How can I remove all Form padding?
struct MyForm: View {
var body: some View {
Form {
Image(uiImage: someImage)
.resizable()
.aspectRatio(contentMode: .fill)
.frame(width: UIScreen.main.bounds.width)
TextField("Name", text: $name)
// Other fields
}
}
}
I know that the underlying view for Form is a UITableView where I can do things like UITableView.appearance().backgroundColor = .clear to change the Form appearance, but I can't figure out how to remove the leading padding.
I also know I can move the Image view outside the Form and put everything in a stack, but that creates other issues with scrolling that I'd like to avoid.
Here is a solution. Tested with Xcode 11.4 / iOS 13.4
Image(uiImage: someImage)
.resizable()
.aspectRatio(contentMode: .fill)
.listRowInsets(EdgeInsets()) // << this one !!
Note: hardcode to UIScreen.main.bounds.width is not needed
I'm creating an iOS app using Apple's SwiftUI framework. As I need to detect if the user taps on a specific area of the screen, I obviously use a button.
The problem is that the area contains an Image and a Text, and as the button automatically gives its content the blue color, the image is also colored, so instead of being an Image it's just a blue rounded rectangle.
It is said that an image is worth a thousand words, and as I'm not good at explaining, here you have a graphic demonstration of what happens:
Outside the button (without button styling)
Inside the button (with button styling)
This happens because the button is adding .foregroundColor(.blue) to the image.
How can I avoid/disable the button adding style to its components?
EDIT: This is my button code:
ContentView.swift:
Button(action: {/* other code */}) {
PackageManagerRow(packageManager: packageManagersData[0])
}
PackageManagerRow.swift:
struct PackageManagerRow : View {
var packageManager : PackageManager
var body: some View {
VStack {
HStack {
Image(packageManager.imageName)
.resizable()
.frame(width: 42.0, height: 42.0)
Text(verbatim: packageManager.name)
Spacer()
Image(systemName: "checkmark")
.foregroundColor(.blue)
.opacity(0)
}.padding(.bottom, 0)
Divider()
.padding(.top, -3)
}
}
}
I think this is from the rendering mode for the image you are using.
Where you have Image("Cydia logo") (or whatever).
You should be setting the rendering mode like...
Image("Cydia Logo").renderingMode(.original)
You can also add a PlainButtonStyle() to your button to avoid iOS style behaviors.
Something like that with your example :
Button(action: {/* other code */}) {
PackageManagerRow(packageManager: packageManagersData[0])
}.buttonStyle(PlainButtonStyle())
I hope it will help you!
Another option is to not use a Button wrapper, but instead use tapAction directly on the Image to trigger your action when the image is pressed
HStack {
Button(action: {
print("Tapped")
}, label: {
Image("Logo").renderingMode(.original) // Add Rendering Mode
})
Text("Cydia")
}
A button with an icon! How original 😀.
If you are dealing with SF symbols then the following will do fine:
Button(action: addItem) {
Text(Image(systemName: "plus").renderingMode(.original))
+
Text("This is Plus")
}
.font(.system(size: 42))
The limitation of the option above is you don't have control over Image's size. So for custom images the following is more appropriate:
Button(action: addItem) {
Label(
title: { Text("Label").font(.system(size: 40)) }, // Any font you like
icon: { Image(systemName: "rectangle.and.pencil.and.ellipsis") // Both custom and system images, i.e. `Image("Cydia logo")`
.renderingMode(.original)
.resizable()
.aspectRatio(contentMode: .fit)
.frame(width: 42, height: 42) // Any size you like
.padding() // Any padding you need
} // and etc.
)
}
Apply the style .plain to your button to avoid overlay color.
// Before
Button(...)
// After
Button(...)
.buttonStyle(.plain) // Remove the overlay color (blue) for images inside Button
.plain button style, that doesn’t style or decorate its content while idle, but may apply a visual effect to indicate the pressed, focused, or enabled state of the button.
Another solution is to custom the style with ButtonStyle
like: struct MyButtonStyle:ButtonStyle { }
You have to render the original image by adding .renderingMode(.original) right after your image declaration.
Image("your_image_name")
.renderingMode(.original)