Core Data: Beyond the Basics
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While sort descriptors can be handy to initially sort data coming out of the persistent store, you might want to provide your user the chance to sort the data in real time as they use your app. Luckily some improvements to Core Data in recent years has made that possible. Both sort descriptors and predicates for fetch requests are accessible outside of the initial fetch request declaration and can be changed on the fly. Let’s add a sort button to the Launches view.
let sortTypes = [
(name: "Name", descriptors: [SortDescriptor(\RocketLaunch.name, order: .forward)]),
(name: "LaunchDate", descriptors: [SortDescriptor(\RocketLaunch.launchDate, order: .forward)])
]
@State var activeSortIndex = 0
.onChange(of: activeSortIndex) { _ in
launches.sortDescriptors = sortTypes[activeSortIndex].descriptors
}
.toolbar {
Menu(content: {
Picker(
selection: $activeSortIndex,
content: {
ForEach(0..<sortTypes.count, id: \.self) { index in
let sortType = sortTypes[index]
Text(sortType.name)
}
},
label: {}
)
}, label: {
Image(systemName: "line.3.horizontal.decrease.circle.fill")
})
}