Realm官方Integration Guides教程
2个月前 • 186次点击 • 来自 iOS
参考链接：
Use Realm Database with SwiftUI and Combine
之前在UIKit下使用Realm的工程经验在SwiftUI与Combine框架只是经验罢了，还是得重新跟着官方教程来一遍。
Swift Packages 添加依赖：
https://github.com/realm/realm-cocoa
官方Integration Guides教程适合学习如何SDK集成与Realm的基础使用：
Use Realm Database with SwiftUI and Combine
1. Get Started
新建一个工程，导入库
import RealmSwift
import Combine
import SwiftUI
2.Define Models
- 其中
randomAdjectives与randomNouns用于产生随机数据 - Group 包含多个 Item(一对多)
- Item包含 2 个属性 : name , isFavorite
/// Random adjectives for more interesting demo item names
let randomAdjectives = [
"fluffy", "classy", "bumpy", "bizarre", "wiggly", "quick", "sudden",
"acoustic", "smiling", "dispensable", "foreign", "shaky", "purple", "keen",
"aberrant", "disastrous", "vague", "squealing", "ad hoc", "sweet"
]
/// Random noun for more interesting demo item names
let randomNouns = [
"floor", "monitor", "hair tie", "puddle", "hair brush", "bread",
"cinder block", "glass", "ring", "twister", "coasters", "fridge",
"toe ring", "bracelet", "cabinet", "nail file", "plate", "lace",
"cork", "mouse pad"
]
/// An individual item. Part of a `Group`.
final class Item: Object, ObjectKeyIdentifiable {
/// The unique ID of the Item. `primaryKey: true` declares the
/// _id member as the primary key to the realm.
@Persisted(primaryKey: true) var _id: ObjectId
/// The name of the Item, By default, a random name is generated.
@Persisted var name = "\(randomAdjectives.randomElement()!) \(randomNouns.randomElement()!)"
/// A flag indicating whether the user "favorited" the item.
@Persisted var isFavorite = false
/// The backlink to the `Group` this item is a part of.
@Persisted(originProperty: "items") var group: LinkingObjects<Group>
}
/// Represents a collection of items.
final class Group: Object, ObjectKeyIdentifiable {
/// The unique ID of the Group. `primaryKey: true` declares the
/// _id member as the primary key to the realm.
@Persisted(primaryKey: true) var _id: ObjectId
/// The collection of Items in this group.
@Persisted var items = RealmSwift.List<Item>()
}
3.Views and Observed Objects
View视图ContentView，LocalOnlyContenteView，ItemsView：
其中，ContentView是工程入口，官方教程是直接让笔者删除了其他模板代码，ContentView继承SwiftUI.App。
LocalOnlyContenteView为工程主视图，ItemsView为LocalOnlyContenteView子视图。
ContentView:
/// The main screen that determines whether to present the SyncContentView or the LocalOnlyContentView.
/// For now, it always displays the LocalOnlyContentView.
@main
struct ContentView: SwiftUI.App {
var body: some Scene {
WindowGroup {
LocalOnlyContentView()
}
}
}
LocalOnlyContenteView:
/// The main content view if not using Sync.
struct LocalOnlyContentView: View {
// Implicitly use the default realm's objects(Group.self)
@ObservedResults(Group.self) var groups
var body: some View {
if let group = groups.first {
AnyView(ItemsView(group: group))
} else {
// For this small app, we only want one group in the realm.
// You can expand this app to support multiple groups.
// For now, if there is no group, add one here.
AnyView(ProgressView().onAppear {
$groups.append(Group())
})
}
}
}
ItemsView：
/// The screen containing a list of items in a group. Implements functionality for adding, rearranging,
/// and deleting items in the group.
struct ItemsView: View {
/// The group is a container for a list of items. Using a group instead of all items
/// directly allows us to maintain a list order that can be updated in the UI.
@ObservedRealmObject var group: Group
/// The button to be displayed on the top left.
var leadingBarButton: AnyView?
var body: some View {
NavigationView {
VStack {
// The list shows the items in the realm.
List {
ForEach(group.items) { item in
ItemRow(item: item)
}.onDelete(perform: $group.items.remove)
.onMove(perform: $group.items.move)
}.listStyle(GroupedListStyle())
.navigationBarTitle("Items", displayMode: .large)
.navigationBarBackButtonHidden(true)
.navigationBarItems(
leading: self.leadingBarButton,
// Edit button on the right to enable rearranging items
trailing: EditButton())
// Action bar at bottom contains Add button.
HStack {
Spacer()
Button(action: {
// The bound collection automatically
// handles write transactions, so we can
// append directly to it.
$group.items.append(Item())
}) { Image(systemName: "plus") }
}.padding()
}
}
}
}
继续完善ItemsView视图的子视图ItemRow，以及点击ItemRow后跳转的视图ItemDetailsView：
/// Represents an Item in a list.
struct ItemRow: View {
@ObservedRealmObject var item: Item
var body: some View {
// You can click an item in the list to navigate to an edit details screen.
NavigationLink(destination: ItemDetailsView(item: item)) {
Text(item.name)
if item.isFavorite {
// If the user "favorited" the item, display a heart icon
Image(systemName: "heart.fill")
}
}
}
}
/// Represents a screen where you can edit the item's name.
struct ItemDetailsView: View {
@ObservedRealmObject var item: Item
var body: some View {
VStack(alignment: .leading) {
Text("Enter a new name:")
// Accept a new name
TextField("New name", text: $item.name)
.navigationBarTitle(item.name)
.navigationBarItems(trailing: Toggle(isOn: $item.isFavorite) {
Image(systemName: item.isFavorite ? "heart.fill" : "heart")
})
}.padding()
}
}
结论
以上为基础使用，如果需使用Realm提供的数据云同步等功能，请继续阅读原文Integrate MongoDB Realm and Sync
完整代码(Without Sync)：
import RealmSwift
import Combine
import SwiftUI
// MARK: Models
/// Random adjectives for more interesting demo item names
let randomAdjectives = [
"fluffy", "classy", "bumpy", "bizarre", "wiggly", "quick", "sudden",
"acoustic", "smiling", "dispensable", "foreign", "shaky", "purple", "keen",
"aberrant", "disastrous", "vague", "squealing", "ad hoc", "sweet"
]
/// Random noun for more interesting demo item names
let randomNouns = [
"floor", "monitor", "hair tie", "puddle", "hair brush", "bread",
"cinder block", "glass", "ring", "twister", "coasters", "fridge",
"toe ring", "bracelet", "cabinet", "nail file", "plate", "lace",
"cork", "mouse pad"
]
/// An individual item. Part of a `Group`.
final class Item: Object, ObjectKeyIdentifiable {
/// The unique ID of the Item. `primaryKey: true` declares the
/// _id member as the primary key to the realm.
@Persisted(primaryKey: true) var _id: ObjectId
/// The name of the Item, By default, a random name is generated.
@Persisted var name = "\(randomAdjectives.randomElement()!) \(randomNouns.randomElement()!)"
/// A flag indicating whether the user "favorited" the item.
@Persisted var isFavorite = false
/// The backlink to the `Group` this item is a part of.
@Persisted(originProperty: "items") var group: LinkingObjects<Group>
}
/// Represents a collection of items.
final class Group: Object, ObjectKeyIdentifiable {
/// The unique ID of the Group. `primaryKey: true` declares the
/// _id member as the primary key to the realm.
@Persisted(primaryKey: true) var _id: ObjectId
/// The collection of Items in this group.
@Persisted var items = RealmSwift.List<Item>()
}
// MARK: Views
// MARK: Main Views
/// The main screen that determines whether to present the SyncContentView or the LocalOnlyContentView.
/// For now, it always displays the LocalOnlyContentView.
@main
struct ContentView: SwiftUI.App {
var body: some Scene {
WindowGroup {
LocalOnlyContentView()
}
}
}
/// The main content view if not using Sync.
struct LocalOnlyContentView: View {
// Implicitly use the default realm's objects(Group.self)
@ObservedResults(Group.self) var groups
var body: some View {
if let group = groups.first {
AnyView(ItemsView(group: group))
} else {
// For this small app, we only want one group in the realm.
// You can expand this app to support multiple groups.
// For now, if there is no group, add one here.
AnyView(ProgressView().onAppear {
$groups.append(Group())
})
}
}
}
// MARK: Item Views
/// The screen containing a list of items in a group. Implements functionality for adding, rearranging,
/// and deleting items in the group.
struct ItemsView: View {
/// The group is a container for a list of items. Using a group instead of all items
/// directly allows us to maintain a list order that can be updated in the UI.
@ObservedRealmObject var group: Group
/// The button to be displayed on the top left.
var leadingBarButton: AnyView?
var body: some View {
NavigationView {
VStack {
// The list shows the items in the realm.
List {
ForEach(group.items) { item in
ItemRow(item: item)
}.onDelete(perform: $group.items.remove)
.onMove(perform: $group.items.move)
}.listStyle(GroupedListStyle())
.navigationBarTitle("Items", displayMode: .large)
.navigationBarBackButtonHidden(true)
.navigationBarItems(
leading: self.leadingBarButton,
// Edit button on the right to enable rearranging items
trailing: EditButton())
// Action bar at bottom contains Add button.
HStack {
Spacer()
Button(action: {
// The bound collection automatically
// handles write transactions, so we can
// append directly to it.
$group.items.append(Item())
}) { Image(systemName: "plus") }
}.padding()
}
}
}
}
/// Represents an Item in a list.
struct ItemRow: View {
@ObservedRealmObject var item: Item
var body: some View {
// You can click an item in the list to navigate to an edit details screen.
NavigationLink(destination: ItemDetailsView(item: item)) {
Text(item.name)
if item.isFavorite {
// If the user "favorited" the item, display a heart icon
Image(systemName: "heart.fill")
}
}
}
}
/// Represents a screen where you can edit the item's name.
struct ItemDetailsView: View {
@ObservedRealmObject var item: Item
var body: some View {
VStack(alignment: .leading) {
Text("Enter a new name:")
// Accept a new name
TextField("New name", text: $item.name)
.navigationBarTitle(item.name)
.navigationBarItems(trailing: Toggle(isOn: $item.isFavorite) {
Image(systemName: item.isFavorite ? "heart.fill" : "heart")
})
}.padding()
}
}
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