Assigning MyScruct().var = results results in no assignment - swift

Question

Ok.. probably bad title. But here, the problem.
struct DeckView: View {
#State public var results = [ScryfallCard]()
var body: some View {
List(results, id: \.id ) { item in
Mkae a list containing the results.
}.onAppear {
ScryfallData().parseBulkData()
print("Type of results::", type(of: results))
print("results.capacity:", results.capacity)
}
}
}
struct ScryfallData {
func parseBulkData() {
let fm = FileManager.default
let path = Bundle.main.resourcePath
let items = try! fm.contentsOfDirectory(atPath: path!)
var oracleFileName = ""
for fileName in items {
if fileName .hasPrefix("oracle-cards"){
oracleFileName = fileName
}
}
print("if let savedJson = Bundle.main.url")
if let savedJson = Bundle.main.url(forResource: oracleFileName, withExtension: "") {
if let dataOfJson = try? Data(contentsOf: savedJson) {
print("if let dataOfJSON: \(dataOfJson)")
do {
let scryfallDecodeData = try JSONDecoder().decode([ScryfallCard].self, from: dataOfJson)
print("scryfallDecodeData.capacity:", scryfallDecodeData.capacity)
/* error here*/ DeckView().results = scryfallDecodeData
print("DeckView().results: ", DeckView().results)
print("Decoded data:", type(of: scryfallDecodeData))
} catch {
debugPrint("decode failed")
}
}
}
}
}
I keep getting a blank List this in the debugger...
if let dataOfJSON: 73545913 bytes
scryfallDecodeData.capacity: 24391
DeckView().results: []
Decoded data: Array<ScryfallCard>
Type of results:: Array<ScryfallCard>
results.capacity: 0
This means that oiver on the line marked Error Here, I'm asigning the decoded data to the DeckView().results var, but the end result is the data is not getting asigned. Any idea what I'm doing wrong?

Answer 1

You should not be creating a View from view model (ScryfallData), but instead return the decoded data from the parseBulkData function and assign that to results inside the onAppear of your View.
Your models should never know about your UI. Your UI (View in case of SwiftUI) should own the models, not the other way around. This achieves good separation of concerns and also makes your business logic platform and UI agnostic.
struct DeckView: View {
#State public var results = [ScryfallCard]()
var body: some View {
List(results, id: \.id ) { item in
Text(item.text)
}.onAppear {
self.results = ScryfallData().parseBulkData()
}
}
}
struct ScryfallData {
func parseBulkData() -> [ScryfallCard] {
let fm = FileManager.default
let path = Bundle.main.resourcePath
let items = try! fm.contentsOfDirectory(atPath: path!)
var oracleFileName = ""
for fileName in items {
if fileName .hasPrefix("oracle-cards"){
oracleFileName = fileName
}
}
if let savedJson = Bundle.main.url(forResource: oracleFileName, withExtension: "") {
do {
let jsonData = try Data(contentsOf: savedJson)
let scryfallDecodeData = try JSONDecoder().decode([ScryfallCard].self, from: jsonData)
return scryfallDecodeData
} catch {
debugPrint("decode failed")
return []
}
}
return []
}
}