SwiftUI 2.0:使用.fileExporter修饰符导出图像 [英] SwiftUI 2.0: export images with .fileExporter modifier
问题描述
目标:使用新的.fileExporter修饰符通过SwiftUI导出图像
Goal: export images with SwiftUI using the new .fileExporter modifier
问题:目标图像未传递到.fileExporter文档.
Problem: The target image is not passing to .fileExporter document.
问题:如何获取.fileExporter修饰符以导出图像?
Question: How can I get .fileExporter modifier to export images?
struct ContentView: View {
@State private var openFile = false
@State private var exportFile = false
@State private var img1 = UIImage()
@State private var img2 = UIImage()
@State private var target: Binding<UIImage>? // dynamic target for importer
var body: some View {
Form {
//image 1
Button(action: {
self.target = $img1
self.openFile.toggle()
}){
Image(uiImage: self.img1)
.renderingMode(.original)
.resizable()
.frame(width: 48, height: 48)
.clipShape(Circle())
}
//image 2
Button(action: {
self.target = $img2
self.openFile.toggle()
}){
Image(uiImage: self.img2)
.renderingMode(.original)
.resizable()
.frame(width: 48, height: 48)
.clipShape(Circle())
}
}
.navigationTitle("File Importer")
//file exporter not working. not sure what I should input as "document"
.fileExporter(isPresented: $exportFile, document: target, contentType: .image) { result in
if case .success = result {
// Handle success.
} else {
// Handle failure.
}
}
//file importer
.fileImporter(isPresented: $openFile, allowedContentTypes: [.image]) { (res) in
do{
let fileUrl = try res.get()
print(fileUrl)
guard fileUrl.startAccessingSecurityScopedResource() else { return }
if let imageData = try? Data(contentsOf: fileUrl),
let image = UIImage(data: imageData) {
self.target?.wrappedValue = image
}
fileUrl.stopAccessingSecurityScopedResource()
} catch{
print ("error reading")
print (error.localizedDescription)
}
}
}
}
推荐答案
我发现了两个代码问题和两个逻辑问题.这是我的编辑版本:
There were a couple of code problems and a couple of logic problems that I found. Here's my edited version:
struct ContentView: View {
@State private var openFile = false
@State private var exportFile = false
@State private var img1 = UIImage(named: "0")!
@State private var img2 = UIImage(named: "1")!
@State private var target : UIImage?
var body: some View {
Form {
//image 1
Button(action: {
self.target = img1
self.exportFile.toggle()
//self.openFile.toggle()
}){
Image(uiImage: self.img1)
.renderingMode(.original)
.resizable()
.frame(width: 48, height: 48)
.clipShape(Circle())
}
//image 2
Button(action: {
self.target = img2
self.exportFile.toggle()
//self.openFile.toggle()
}){
Image(uiImage: self.img2)
.renderingMode(.original)
.resizable()
.frame(width: 48, height: 48)
.clipShape(Circle())
}
}
.navigationTitle("File Importer")
.fileExporter(isPresented: $exportFile, document: ImageDocument(image: target), contentType: .png, onCompletion: { (result) in
if case .success = result {
print("Success")
} else {
print("Failure")
}
})
//file importer
.fileImporter(isPresented: $openFile, allowedContentTypes: [.image]) { (res) in
do{
let fileUrl = try res.get()
print(fileUrl)
guard fileUrl.startAccessingSecurityScopedResource() else { return }
if let imageData = try? Data(contentsOf: fileUrl),
let image = UIImage(data: imageData) {
self.target = image
}
fileUrl.stopAccessingSecurityScopedResource()
} catch{
print ("error reading")
print (error.localizedDescription)
}
}
}
}
struct ImageDocument: FileDocument {
static var readableContentTypes: [UTType] { [.png] }
var image: UIImage
init(image: UIImage?) {
self.image = image ?? UIImage()
}
init(configuration: ReadConfiguration) throws {
guard let data = configuration.file.regularFileContents,
let image = UIImage(data: data)
else {
throw CocoaError(.fileReadCorruptFile)
}
self.image = image
}
func fileWrapper(configuration: WriteConfiguration) throws -> FileWrapper {
return FileWrapper(regularFileWithContents: image.pngData()!)
}
}
要看的东西:
- 逻辑错误:您有一个
exportFile
状态变量,但从未修改过它.这意味着fileExporter
将永远不会出现. - 您正在将
Binding< UIImage>
传递给需要FileDocument
的函数.我为图像编写了一个简单的FileDocument
实现. - 因为我将您的
openFile
开关切换为exportFile
,所以您现在没有任何openFile
访问权限.这是您决定何时/如何触发这些的逻辑决定. - 我也没有对图像进行任何错误处理,因此决定将所有内容都视为PNG.您可能需要做出不同的选择.
- Logic error: you had an
exportFile
state variable, but you never modified it. That would meanfileExporter
would never present. - You were passing a
Binding<UIImage>
to a function that wants aFileDocument
. I wrote a simpleFileDocument
implementation for images. - Because I switched out your
openFile
toggles forexportFile
, you now don't have anyopenFile
access. That's a logic decision for you to figure out when/how to trigger those. - I also didn't do any error handling for the images and made a decision to treat everything as a PNG. You may want to make different choices.
请注意,我还使用了名为"0"的图像,和"1"表示-这些是我的示例项目所特有的.更改这些内容以适合您的项目.
Note that I also used images named "0" and "1" -- those were specific to my sample project. Change those to fit what works for your project.
如果您需要其他类型的解决方案,也可以使用 \.exportFiles
操作:
If you want a different type of solution to this, you can also look at using the \.exportFiles
action: https://www.hackingwithswift.com/quick-start/swiftui/how-to-export-files-using-exportfilesaction
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