[英]Loop through entity array in SwiftUI to build tree-structured view based on values in array data
I'm totally new to Swift.我对 Swift 完全陌生。 I need to traverse an array, and based on what the data is, build out a custom tree structure.我需要遍历一个数组,并根据数据是什么,构建一个自定义的树结构。 I would share my code but it's too bulky and too horrible to be seen in public.我会分享我的代码,但它太笨重,太可怕了,不能在公共场合看到。 It's not even close to working.它甚至不接近工作。 So here's some pseudocode instead:所以这里有一些伪代码:
pass in an array of ScheduleCell models (data for a scheduled tv program) to a SwiftUI View.
Each ScheduleCell contains:
Date of broadcast
Channel
Starttime
Program title, subtitle, etc
in the view body, loop over each ScheduleCell
if ScheduleCell is new day then
display new date
go down one line
end
if ScheduleCell is new channel then
display ScheduleCell.channel but do NOT drop down a line
end
display ScheduleCell.title, also on same line as channel
Keep going on the same horizontal line till you hit the next channel
end
The end effect should be like this:最终效果应该是这样的:
11-16-2021
CNN News Program 1 News Program 2 News Program 3 Etc.
NBC Late Show Infomercial Barney Miller Rerun. Etc.
11-17-2021
CNN News Program 1 News Program 2 News Program 3 Etc.
NBC Late Show Infomercial Barney Miller Rerun. Etc.
It seems like it should be really simple to do this.这样做似乎应该很简单。 I've tried setting up a tree structure, but I'm having trouble with the SwiftUI View protocol.我试过设置树结构,但我在使用 SwiftUI View 协议时遇到了问题。 I have tried building the tree structure in a function outside of the view body, but I'm having trouble figuring out how to get that structure into the view body.我曾尝试在视图主体之外的函数中构建树结构,但我无法弄清楚如何将该结构放入视图主体中。
In the alternative, I've backed off all that to just trying to get it to work via brute force inside the view by tracking the array index, like this:或者,我已经放弃了所有这些,只是试图通过跟踪数组索引在视图中通过蛮力使其工作,如下所示:
struct ScheduleDisplayView: View {
var schedule: [SchedSlot]
let dfdo = DateFormatter.dateOnly
let dfto = DateFormatter.timeOnly
let chanwidth: CGFloat = 45.0
let fontsize: CGFloat = 10.0
var body: some View {
List {
ForEach(schedule.indices,id:\.self) { idx in
let ssDay: String = dfdo.string(from: schedule[idx].startTime!)
let ssChan: Int32 = schedule[idx].channel!.channelID
if idx == 0 ||
ssDay != dfdo.string(from: schedule[idx-1].startTime!)
{
VStack {
Text(ssDay)
.frame(maxWidth: 200 + chanwidth, alignment: .leading)
}
}
HStack {
if idx == 0 ||
ssChan != schedule[idx-1].channel!.channelID
{
VStack {
Text(String(schedule[idx].channel!.channelID))
.frame(maxWidth: chanwidth, alignment: .center)
//.font(.system(size: fontsize))
Text(schedule[idx].channel!.callSign!)
.frame(maxWidth: chanwidth, alignment: .center)
//.font(.system(size: fontsize))
}
}
Text(schedule[idx].program!.title!)
.frame(maxWidth: 200, alignment: .leading)
.border(Color.black)
}
}
}
}
}
But the above approach isn't working because the HStack can't keep the program titles on the same line.但是上述方法不起作用,因为 HStack 无法将程序标题保持在同一行上。
Thanks in advance for any input.提前感谢您的任何意见。
Additional material:补充材料:
Here's a few random slices of the CoreData entities this is based on:这是基于的 CoreData 实体的一些随机切片:
SchedCell
stationID starttime programID duration endtime isUsed channel program
34916 2021-09-29 19:09:00.000 EP000045050088 PT00H09M 2021-09-29 19:18:00.000 0
12131 2021-09-29 19:15:00.000 EP022222100024 PT00H15M 2021-09-29 19:30:00.000 0
34916 2021-09-29 19:18:00.000 EP000045050208 PT00H09M 2021-09-29 19:27:00.000 0
Program
series programID title subtitle fulldescription genre isUsed
EP00000066 EP000000660001 A Pup Named Scooby-Doo Night of the Living Burger After a quarrel, a burgerlike creature haunts Shaggy and Scooby. Children 0
EP00000066 EP000000660002 A Pup Named Scooby-Doo For Letter or Worse The ghost of a long-dead gangster haunts a TV studio. Children 0
EP00000066 EP000000660003 A Pup Named Scooby-Doo A Bicycle Built for Boo! A green monster steals Shaggy's bike. Children 0
EP00000066 EP000000660004 A Pup Named Scooby-Doo The Baby Sitter From Beyond The baby sitter for Shaggy's little sister appears to be a monster. Children 0
Channel
stationID callSign fullName channelID isUsed
15722 WCIX WCIX 2 0
11345 WCIA WCIA 3 0
11278 WAND WAND 4 0
10685 KSDK KSDK 5 0
10269 HSN Home Shopping Network 6 0
11824 WRSP WRSP 7 0
11069 QVC QVC 8 0
As for code samples of my attempts to build the tree structure outside of the view, I have no working code.至于我尝试在视图之外构建树结构的代码示例,我没有工作代码。 It's all just fragments that produced a variety of error messages.这只是产生各种错误消息的片段。 Here are the node structures.下面是节点结构。 I'm still working out a routine to assemble them into a working tree, will post that as soon as I have something worth looking at:我仍在制定一个例程将它们组装成一个工作树,一旦我有值得一看的东西就会发布:
class RootNode {
var children: [DayNode] = []
func add(child: DayNode) {
children.append(child)
child.parent = self
}
}
class DayNode {
var parent: RootNode
var date: String
var children: [ChannelNode] = []
init(date: String) {
self.date = date
}
func add(child: ChannelNode) {
children.append(child)
child.parent = self
}
}
class ChannelNode {
var parent: DayNode
var channel: String
var children: [SchedSlot] = []
init(channel: String) {
self.channel = channel
}
func add(child: SchedSlot) {
children.append(child)
//child.parent = self
}
}
As I mentioned in the comments, I think this is more of a data organization/sorting issue than a SwiftUI layout issue.正如我在评论中提到的,我认为这更像是一个数据组织/排序问题,而不是 SwiftUI 布局问题。 If you data is grouped and sorted correctly, the layout becomes more trivial (eg you don't have to try to decide whether to break a line because of a new channel).如果您对数据进行了正确的分组和排序,则布局将变得更加简单(例如,您不必尝试决定是否因为新通道而断线)。
In the following example, I spend the bulk of the code grouping and sorting the data.在以下示例中,我将大部分代码用于对数据进行分组和排序。 Then, the layout itself is relatively simple.然后,布局本身就比较简单。
It's important to note that I do a couple of unsafe things here for brevity, like using first!
重要的是要注意,为了简洁起见,我在这里做了一些不安全的事情,比如first!
使用first!
that you would want to test for or have contingencies for in real code.您希望在实际代码中测试或有意外情况。
struct SchedCell {
var stationID: Int
var startTime: Date
var programID: String
var channel: String
}
func generateSampleCells() -> [SchedCell] {
let formatter = DateFormatter()
formatter.dateFormat = "yyyy-MM-dd HH:mm:ss.SSS"
return [
("2021-09-29 19:09:00.000",34916,"EP000045050088","PT00H09M"),
("2021-09-29 19:09:00.000",34917,"EP000045050088","PT00H09M"),
("2021-09-29 19:15:00.000",12131,"EP022222100024","PT00H15M"),
("2021-09-29 19:18:00.000",34916,"EP000045050208","PT00H09M"),
("2021-09-30 19:09:00.000",34916,"EP000045050088","PT00H09M"),
("2021-09-30 19:15:00.000",12131,"EP022222100024","PT00H15M"),
("2021-09-30 19:18:00.000",34916,"EP000045050208","PT00H09M"),
("2021-09-30 19:15:00.000",12132,"EP022222100024","PT00H15M"),
("2021-09-29 19:09:00.000",4916,"EP000045050088","PT00H09M"),
("2021-09-29 19:09:00.000",4917,"EP000045050088","PT00H09M"),
("2021-09-29 19:15:00.000",2131,"EP022222100024","PT00H15M"),
].map {
SchedCell(stationID: $0.1, startTime: formatter.date(from: $0.0)!, programID: $0.2, channel: $0.3)
}
}
struct ContentView: View {
private var data = generateSampleCells()
private var formatter = DateFormatter()
struct ScheduleDay {
var dateStamp: String
var date : Date
var channels: [ChannelLineup]
}
struct ChannelLineup {
var channelName: String
var programs: [SchedCell]
}
struct DateStampedSchedCell {
var dateStamp: String
var cell: SchedCell
}
var sortedData : [ScheduleDay] {
formatter.dateFormat = "MM-dd-yyyy"
let dateStamped = data
.map { item -> DateStampedSchedCell in
DateStampedSchedCell(dateStamp: formatter.string(from: item.startTime), cell: item)
}
let days = Dictionary(grouping: dateStamped, by: { $0.dateStamp} ).values
let channelMappedDays = days.map { day in
ScheduleDay(dateStamp: day.first!.dateStamp,
date: day.first!.cell.startTime,
channels: Dictionary(grouping: day, by: { $0.cell.channel }).map { ChannelLineup(channelName: $0.key, programs: $0.value.map(\.cell))}
)
}.sorted(by: {a,b in a.date < b.date})
return channelMappedDays
}
var body: some View {
ScrollView(.horizontal) {
ForEach(sortedData, id: \.dateStamp) { day in
VStack(alignment: .leading) {
Text("Day: \(day.dateStamp)")
.bold()
ForEach(day.channels, id: \.channelName) { channel in
HStack {
Text("Channel: \(channel.channelName)")
.foregroundColor(.red)
ForEach(channel.programs, id: \.programID) { program in
Text(program.programID)
}
}
}
}.frame(maxWidth: .infinity, alignment: .leading)
}
}
}
}
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