Wiki

User Tools

Site Tools

Trace:
swift

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revisionPrevious revision
Next revision		Previous revision
swift [2023/11/19 22:13] – adminswift [2023/11/19 22:16] (current) – admin
Line 77: Line 77:
 [[https://developer.apple.com/library/archive/documentation/General/Conceptual/iCloudDesignGuide/Chapters/DesigningForKey-ValueDataIniCloud.html#//apple_ref/doc/uid/TP40012094-CH7|Apple: Designing for Key-Value Data in iCloud]] [[https://developer.apple.com/library/archive/documentation/General/Conceptual/iCloudDesignGuide/Chapters/DesigningForKey-ValueDataIniCloud.html#//apple_ref/doc/uid/TP40012094-CH7|Apple: Designing for Key-Value Data in iCloud]]
  
-### Relationship Between Entities in CoreData+### Relationship: Connect entities in CoreData
 ref: https://www.hackingwithswift.com/books/ios-swiftui/one-to-many-relationships-with-core-data-swiftui-and-fetchrequest ref: https://www.hackingwithswift.com/books/ios-swiftui/one-to-many-relationships-with-core-data-swiftui-and-fetchrequest
-Step by Step: 
  
 1. Create Entities in CoreData 1. Create Entities in CoreData
Line 87: Line 86:
 5. In `...CoreDataProperties` file, you should be able to see code like below for adding transactions to this certain piggy object. 5. In `...CoreDataProperties` file, you should be able to see code like below for adding transactions to this certain piggy object.
  
-```swift+```
 extension Piggy { extension Piggy {
  
Line 121: Line 120:
 2. In  ` ...CoreDataProperties` file, `transactions` is an `NSSet`, perform the following steps to convert it from an `NSSet` to a `Set<PurchasedItem>` – a Swift-native type where the types of its contents is specificy to `PurchasedItem` type. Convert that `Set<PurchasedItem>` into an array, so that `ForEach` can read individual values from there. Sort that array, so the transactions come in a sensible order. 2. In  ` ...CoreDataProperties` file, `transactions` is an `NSSet`, perform the following steps to convert it from an `NSSet` to a `Set<PurchasedItem>` – a Swift-native type where the types of its contents is specificy to `PurchasedItem` type. Convert that `Set<PurchasedItem>` into an array, so that `ForEach` can read individual values from there. Sort that array, so the transactions come in a sensible order.
  
-```swift+```
    public var transactionArray: [PurchasedItem] {    public var transactionArray: [PurchasedItem] {
        let set = transactions as? Set<PurchasedItem> ?? []        let set = transactions as? Set<PurchasedItem> ?? []
Line 133: Line 132:
 1. Use them in your View: To read purchased items connected to a certain piggy in a View. Use the following code: 1. Use them in your View: To read purchased items connected to a certain piggy in a View. Use the following code:
  
-```swift+```
    struct HistoryView: View {    struct HistoryView: View {
        @Environment(\.managedObjectContext) private var viewContext        @Environment(\.managedObjectContext) private var viewContext
Line 165: Line 164:
 Or use the following code. However with this method the HistoryView won't update if you add new purchasedItem (transaction) because it is only monitoring the object `piggy`. To trigger view update when purchasedItem is added, you need to use the method above to fetch `PurchasedItem` directly. Or use the following code. However with this method the HistoryView won't update if you add new purchasedItem (transaction) because it is only monitoring the object `piggy`. To trigger view update when purchasedItem is added, you need to use the method above to fetch `PurchasedItem` directly.
  
-```swift+```
 struct HistoryView: View { struct HistoryView: View {
    @Environment(\.managedObjectContext) private var viewContext    @Environment(\.managedObjectContext) private var viewContext
swift.1700403186.txt.gz · Last modified: (external edit)