{"id":4882,"date":"2022-01-15T20:44:26","date_gmt":"2022-01-15T12:44:26","guid":{"rendered":"http:\/\/123.57.164.21\/?p=4882"},"modified":"2022-01-15T20:44:26","modified_gmt":"2022-01-15T12:44:26","slug":"swiftui-2-0-stateobject-%e7%a0%94%e7%a9%b6","status":"publish","type":"post","link":"https:\/\/92it.top\/?p=4882","title":{"rendered":"SwiftUI 2.0 \u2014\u2014 @StateObject \u7814\u7a76"},"content":{"rendered":"\n<p>WWDC20 \u521a\u521a\u7ed3\u675f\uff0c\u5728\u8fc7\u53bb\u7684\u4e00\u5468\uff0c\u82f9\u679c\u4e3a\u5f00\u53d1\u8005\u5e26\u6765\u4e86\u5de8\u5927\u7684\u60ca\u559c\u3002\u7531\u4e8e\u65b0\u7279\u6027\u5b9e\u5728\u592a\u591a\uff0c\u9700\u8981\u4e0d\u5c11\u65f6\u95f4\u6765\u6d88\u5316\uff0c\u6211\u9996\u5148\u9009\u62e9\u81ea\u5df1\u6700\u611f\u5174\u8da3\u7684\u5185\u5bb9\u8fdb\u884c\u4e00\u4e9b\u7b80\u5355\u7684\u7814\u7a76\u548c\u63a2\u8ba8\u3002\u672c\u6587\u9996\u5148\u6d45\u8c08\u4e00\u4e0b SwiftUI \u65b0\u63d0\u4f9b\u7684\u5c5e\u6027\u5305\u88c5\u5668@StateObject\u3002<\/p>\n\n\n\n<h5 class=\"wp-block-heading\">\u4e3a\u4ec0\u4e48\u8981\u65b0\u589e@StateObject<\/h5>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<p>\u5728\u6211\u4e4b\u524d\u7684\u6587\u7ae0 <a href=\"https:\/\/www.fatbobman.com\/posts\/swiftUI-state\/\">@State \u7814\u7a76<\/a> \u4e2d\u6211\u4eec\u63a2\u8ba8\u8fc7@State\uff0c\u901a\u8fc7\u5b83\uff0c\u6211\u4eec\u53ef\u4ee5\u65b9\u4fbf\u7684\u5c06\u503c\u7c7b\u578b\u6570\u636e\u4f5c\u4e3a View \u7684 Source of truth\u3002\u5728 SwiftUI 1.0 \u65f6\u4ee3\uff0c\u5982\u679c\u60f3\u5c06\u5f15\u7528\u7c7b\u578b\u4f5c\u4e3a source of truth, \u901a\u5e38\u7684\u65b9\u6cd5\u662f\u4f7f\u7528@EnvironmentObject \u6216\u8005 @ObservedObject\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">struct RootView:View{\n    var body: some View{\n        ContentView()\n            .environmentObject(Store())\n    }\n}\n\nstruct ContentView: View {\n    @EnvironmentObject  var store1:Store\n    var body: some View {\n        Text(\"count:\\(store.count)\")\n    }\n}\n<\/pre>\n\n\n\n<p>\u5bf9\u4e8e\u4f7f\u7528@EnvironmentObject \u6ce8\u5165\u7684\u6570\u636e\uff0c\u7531\u4e8e\u5176\u901a\u5e38\u662f\u5728 SceneDelegate \u6216\u7740\u5f53\u524d View \u7684\u7236\u8f88\u3001\u7956\u5148 View \u4e0a\u521b\u5efa\u7684\uff0c\u6240\u4ee5\u5176\u751f\u547d\u5468\u671f\u5fc5\u7136\u4e0d\u77ed\u4e8e\u5f53\u524d View, \u56e0\u6b64\u5728\u4f7f\u7528\u4e2d\u5e76\u4e0d\u4f1a\u53d1\u751f\u7531\u4e8e\u751f\u547d\u5468\u671f\u4e0d\u53ef\u9884\u6d4b\u800c\u5bfc\u81f4\u7684\u5f02\u5e38\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">struct Test5: View {\n    @ObservedObject var store = Store()\n    var body: some View {\n        Text(\"count:\\(store.count)\")\n    }\n}\n<\/pre>\n\n\n\n<p>\u5bf9\u4e8e\u4e0a\u9762\u7684\u4ee3\u7801\uff0c\u4e4d\u770b\u8d77\u6765\u6ca1\u6709\u4efb\u4f55\u4e0d\u59a5\uff0c\u4e0d\u8fc7\u7531\u4e8e@ObservedObject \u7684\u673a\u5236\u95ee\u9898\uff0c\u5176\u521b\u5efa\u7684\u5b9e\u4f8b\u5e76\u4e0d\u88ab\u5f53\u524d View \u6240\u62e5\u6709\uff08\u5f53\u524d View \u65e0\u6cd5\u7ba1\u7406\u5176\u751f\u547d\u5468\u671f\uff09\uff0c\u56e0\u6b64\u5728\u4e00\u4e9b\u7279\u6b8a\u7684\u60c5\u51b5\u4e0b\u4f1a\u51fa\u73b0\u4e0d\u53ef\u9884\u6599\u7684\u7ed3\u679c\u3002<\/p>\n\n\n\n<p>\u4e3a\u4e86\u80fd\u591f\u8ba9\u5f00\u53d1\u8005\u66f4\u597d\u7684\u638c\u63a7\u4ee3\u7801\uff0c\u540c\u65f6\u4e5f\u4fdd\u6301\u5bf9\u4e8e\u4e0a\u4e00\u7248\u672c\u826f\u597d\u7684\u517c\u5bb9\u6027\uff0c\u82f9\u679c\u5728 SwiftUI2.0 \u4e2d\u6dfb\u52a0\u4e86@StateObject\u3002\u987e\u540d\u601d\u4e49\uff0c\u5b83\u662f@State \u7684\u5f15\u7528\u7c7b\u578b\u7248\u672c\u3002<\/p>\n\n\n\n<p>\u5728 WWDC \u7684\u89c6\u9891\u4e2d\uff0c\u82f9\u679c\u660e\u786e\u7684\u8868\u660e@StateObject \u662f\u88ab\u521b\u5efa\u4ed6\u7684 View \u6240\u6301\u6709\u7684\uff0c\u4e5f\u5c31\u662f\u8bf4\uff0c\u5b9e\u4f8b\u7684\u751f\u547d\u5468\u671f\u662f\u5b8c\u5168\u53ef\u63a7\u7684\uff0c\u662f\u540c\u521b\u5efa\u5b83\u7684 View \u7684\u751f\u547d\u5468\u671f\u4e00\u6837\u7684\u3002<\/p>\n\n\n\n<p><strong>@StateObject \u548c @ObservedObject \u7684\u533a\u522b\u5c31\u662f\u5b9e\u4f8b\u662f\u5426\u88ab\u521b\u5efa\u5176\u7684 View \u6240\u6301\u6709\uff0c\u5176\u751f\u547d\u5468\u671f\u662f\u5426\u5b8c\u5168\u53ef\u63a7\u3002<\/strong><\/p>\n\n\n\n<h5 class=\"wp-block-heading\">\u901a\u8fc7\u4ee3\u7801\u4e86\u89e3\u4e0d\u540c<\/h5>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<p>\u6211\u901a\u8fc7\u4e0b\u9762\u7684\u4ee3\u7801\u6765\u8be6\u7ec6\u9610\u8ff0\u4e00\u4e0b @StateObject \u548c @ObservedObject \u7684\u4e0d\u540c\u8868\u73b0\u3002<\/p>\n\n\n\n<p><strong>\u51c6\u5907\u5de5\u4f5c\uff1a<\/strong><\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">class StateObjectClass:ObservableObject{\n    let type:String\n    let id:Int\n    @Published var count = 0\n    init(type:String){\n        self.type = type\n        self.id = Int.random(in: 0...1000)\n        print(\"type:\\(type) id:\\(id) init\")\n    }\n    deinit {\n        print(\"type:\\(type) id:\\(id) deinit\")\n    }\n}\n\nstruct CountViewState:View{\n    @StateObject var state = StateObjectClass(type:\"StateObject\")\n    var body: some View{\n        VStack{\n            Text(\"@StateObject count :\\(state.count)\")\n            Button(\"+1\"){\n                state.count += 1\n            }\n        }\n    }\n}\n\nstruct CountViewObserved:View{\n    @ObservedObject var state = StateObjectClass(type:\"Observed\")\n    var body: some View{\n        VStack{\n            Text(\"@Observed count :\\(state.count)\")\n            Button(\"+1\"){\n                state.count += 1\n            }\n        }\n    }\n}<\/pre>\n\n\n\n<p>StateObjectClass \u5c06\u5728\u5176\u88ab\u521b\u5efa\u548c\u9500\u6bc1\u65f6\u901a\u8fc7 type \u548c id \u544a\u77e5\u6211\u4eec\u5b83\u662f\u88ab\u90a3\u79cd\u65b9\u6cd5\u521b\u5efa\u7684\uff0c\u4ee5\u53ca\u5177\u4f53\u54ea\u4e2a\u5b9e\u4f8b\u88ab\u9500\u6bc1\u4e86\u3002<\/p>\n\n\n\n<p>CountViewState \u548c CountViewObserved \u552f\u4e00\u7684\u4e0d\u540c\u662f\u521b\u5efa\u5b9e\u4f8b\u4f7f\u7528\u7684\u5c5e\u6027\u5305\u88c5\u5668\u4e0d\u540c\u3002<\/p>\n\n\n\n<p><strong>\u6d4b\u8bd5 1\uff1a<\/strong><\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">struct Test1: View {\n    @State var count = 0\n    var body: some View {\n        VStack{\n            Text(\"\u5237\u65b0 CounterView \u8ba1\u6570 :\\(count)\")\n            Button(\"\u5237\u65b0\"){\n                count += 1\n            }\n            \n            CountViewState()\n                .padding()\n            \n            CountViewObserved()\n                .padding()\n            \n        }\n    }\n}<\/pre>\n\n\n\n<p>\u5728\u6d4b\u8bd5 1 \u4e2d\uff0c\u5f53\u8fdb\u70b9\u51fb+1 \u6309\u94ae\u65f6\uff0c\u65e0\u8bba\u662f@StateObject \u6216\u662f@ObservedObject \u5176\u90fd\u8868\u73b0\u51fa\u4e00\u81f4\u7684\u72b6\u6001\uff0c\u4e24\u4e2a View \u90fd\u53ef\u4ee5\u6b63\u5e38\u7684\u663e\u793a\u5f53\u524d\u6309\u94ae\u7684\u70b9\u51fb\u6b21\u6570\uff0c\u4e0d\u8fc7\u5f53\u70b9\u51fb\u5237\u65b0\u6309\u94ae\u65f6\uff0cCountViewState \u4e2d\u7684\u6570\u503c\u4ecd\u7136\u6b63\u5e38\uff0c\u4e0d\u8fc7 CountViewObserved \u4e2d\u7684\u8ba1\u6570\u503c\u88ab\u6e05\u96f6\u4e86\u3002\u4ece\u8c03\u8bd5\u4fe1\u606f\u53ef\u4ee5\u770b\u51fa\uff0c\u5f53\u70b9\u51fb\u5237\u65b0\u65f6\uff0cCountViewObserved \u4e2d\u7684\u5b9e\u4f8b\u88ab\u91cd\u65b0\u521b\u5efa\u4e86\uff0c\u5e76\u9500\u6bc1\u4e86\u4e4b\u524d\u7684\u5b9e\u4f8b\uff08CountViewObserved \u89c6\u56fe\u5e76\u6ca1\u6709\u88ab\u91cd\u65b0\u521b\u5efa\uff0c\u4ec5\u662f\u91cd\u65b0\u6c42\u4e86 body \u7684\u503c\uff09\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">type:Observed id:443 init\ntype:Observed id:103 deinit<\/pre>\n\n\n\n<p>\u5728\u8fd9\u4e2a\u6d4b\u8bd5\u4e2d\uff0c@ObservedObject \u521b\u5efa\u7684\u5b9e\u4f8b\u7684\u751f\u547d\u5468\u671f\u77ed\u4e8e\u5f53\u524d View\u3002<\/p>\n\n\n\n<p><strong>\u6d4b\u8bd5 2:<\/strong><\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">struct Test2: View {\n    @State var count = 0\n    var body: some View {\n        NavigationView{\n            List{\n                NavigationLink(\"@StateObject\", destination: CountViewState())\n                NavigationLink(\"@ObservedObject\", destination: CountViewObserved())\n            }\n        }\n    }\n}\n<\/pre>\n\n\n\n<p>\u6d4b\u8bd5 2 \u4e2d\uff0c\u70b9\u51fb link \u8fdb\u5165\u5bf9\u5e94\u7684 View \u540e\u901a\u8fc7\u70b9\u51fb+1 \u8fdb\u884c\u8ba1\u6570\uff0c\u7136\u540e\u8fd4\u56de\u7236\u89c6\u56fe\u3002\u5f53\u518d\u6b21\u8fdb\u5165 link \u540e\uff0c@StateObject \u5bf9\u5e94\u7684\u89c6\u56fe\u4e2d\u8ba1\u6570\u6e05\u96f6\uff08\u7531\u4e8e\u8fd4\u56de\u7236\u89c6\u56fe\uff0c\u518d\u6b21\u8fdb\u5165\u65f6\u4f1a\u91cd\u65b0\u521b\u5efa\u89c6\u56fe\uff0c\u6240\u4ee5\u4f1a\u91cd\u65b0\u521b\u5efa\u5b9e\u4f8b\uff09\uff0c\u4e0d\u8fc7@ObservedObject \u5bf9\u5e94\u7684\u89c6\u56fe\u4e2d\u8ba1\u6570\u662f\u4e0d\u6e05\u96f6\u7684\u3002<\/p>\n\n\n\n<p>\u5728\u8fd9\u4e2a\u6d4b\u8bd5\u4e2d\uff0c@ObservedObject \u521b\u5efa\u7684\u5b9e\u4f8b\u751f\u547d\u5468\u671f\u957f\u4e8e\u5f53\u524d\u7684 View\u3002<\/p>\n\n\n\n<p><strong>\u6d4b\u8bd5 3:<\/strong><\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">struct Test3: View {\n    @State private var showStateObjectSheet = false\n    @State private var showObservedObjectSheet = false\n    var body: some View {\n        List{\n            Button(\"Show StateObject Sheet\"){\n                showStateObjectSheet.toggle()\n            }\n            .sheet(isPresented: $showStateObjectSheet) {\n                CountViewState()\n            }\n            Button(\"Show ObservedObject Sheet\"){\n                showObservedObjectSheet.toggle()\n            }\n            .sheet(isPresented: $showObservedObjectSheet) {\n                CountViewObserved()\n            }   \n        }\n    }\n}<\/pre>\n\n\n\n<p>\u6d4b\u8bd5 3 \u4e2d\u70b9\u51fb\u6309\u94ae\uff0c\u5728 sheet \u4e2d\u70b9\u51fb+1, \u5f53\u518d\u6b21\u8fdb\u5165 sheet \u540e\uff0c\u65e0\u8bba\u662f@StateObject \u8fd8\u662f@ObservedObject \u5bf9\u5e94\u7684 View \u4e2d\u7684\u8ba1\u6570\u90fd\u88ab\u6e05\u96f6\u3002<\/p>\n\n\n\n<p>\u5728\u8fd9\u4e2a\u6d4b\u8bd5\u4e2d\uff0c@ObservedObject \u521b\u5efa\u7684\u5b9e\u4f8b\u751f\u547d\u5468\u671f\u548c View \u662f\u4e00\u81f4\u7684\u3002<\/p>\n\n\n\n<p><strong>\u4e09\u6bb5\u4ee3\u7801\uff0c\u4e09\u79cd\u7ed3\u679c\uff0c\u8fd9\u4e5f\u5c31\u662f\u4e3a\u4ec0\u4e48\u82f9\u679c\u8981\u65b0\u589e@StateObject \u7684\u539f\u56e0\u2014\u2014\u8ba9\u5f00\u53d1\u8005\u53ef\u4ee5\u660e\u786e\u5730\u4e86\u89e3\u5e76\u638c\u63e1\u5b9e\u4f8b\u7684\u751f\u547d\u5468\u671f\uff0c\u6d88\u9664\u4e0d\u786e\u5b9a\u6027\uff01<\/strong><\/p>\n\n\n\n<h5 class=\"wp-block-heading\">ObservedObject \u662f\u5426\u8fd8\u6709\u5b58\u5728\u7684\u5fc5\u8981\uff1f<\/h5>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<p>\u5bf9\u6211\u4e2a\u4eba\u800c\u8a00\uff0c\u57fa\u672c\u5931\u53bb\u4e86\u4f7f\u7528\u5176\u7684\u7406\u7531\uff08\u53ef\u7528\u4e8e\u7ed1\u5b9a\u7236\u89c6\u56fe\u4f20\u9012\u7684@StateObject\uff09\u3002<\/p>\n\n\n\n<p>\u5c3d\u7ba1\u6216\u8bb8\u4e0a\u9762\u4f8b\u5b50\u7684\u67d0\u79cd\u7279\u6027\u53ef\u80fd\u8ba9\u4f60\u89c9\u5f97 ObservedObject \u53ef\u4ee5\u5b8c\u6210\u67d0\u4e9b\u7279\u6b8a\u9700\u6c42\uff08\u6bd4\u5982\u6d4b\u8bd5 2\uff09\uff0c\u4f46\u6211\u4eec\u65e0\u6cd5\u4fdd\u8bc1\u82f9\u679c\u5728\u4e4b\u540e\u4e0d\u6539\u53d8 ObservedObject \u7684\u8fd0\u884c\u673a\u7406\uff0c\u4ece\u800c\u6539\u53d8\u5f53\u524d\u7684\u7ed3\u679c\u3002<\/p>\n\n\n\n<p>\u6211\u4e2a\u4eba\u8fd8\u662f\u66f4\u63a8\u8350\u5c06\u6765\u90fd\u4f7f\u7528@StateObject \u6765\u6d88\u9664\u4ee3\u7801\u8fd0\u884c\u7684\u4e0d\u786e\u5b9a\u6027\u3002<\/p>\n\n\n\n<p>\u901a\u8fc7\u4e0b\u8ff0\u4ee3\u7801\uff0c\u4f7f\u7528@StateObject \u540c\u6837\u53ef\u4ee5\u5f97\u5230\u6d4b\u8bd5 2 \u4e2d ObservedObject \u7684\u8fd0\u884c\u6548\u679c\u3002<\/p>\n\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">struct Test4: View {\n    @State private var showStateObjectSheet = false\n    @StateObject var state = StateObjectClass(type: \"stateObject\")\n    var body: some View {\n        List{\n            Button(\"Show StateObject1 Sheet\"){\n                showStateObjectSheet.toggle()\n            }\n            .sheet(isPresented: $showStateObjectSheet) {\n                CountViewState1(state: state)\n            }\n        }\n    }\n}\n\nstruct CountViewState1:View{\n    @ObservedObject var state:StateObjectClass\n    var body: some View{\n        VStack{\n            Text(\"@StateObject count :\\(state.count)\")\n            Button(\"+1\"){\n                state.count += 1\n            }\n        }\n    }\n}<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>WWDC20 \u521a\u521a\u7ed3\u675f\uff0c\u5728\u8fc7\u53bb\u7684\u4e00\u5468\uff0c\u82f9\u679c\u4e3a\u5f00\u53d1\u8005\u5e26\u6765\u4e86\u5de8\u5927\u7684\u60ca\u559c\u3002\u7531\u4e8e\u65b0\u7279\u6027\u5b9e\u5728\u592a\u591a\uff0c\u9700\u8981\u4e0d\u5c11\u65f6\u95f4\u6765\u6d88\u5316\uff0c\u6211 [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6,5],"tags":[],"_links":{"self":[{"href":"https:\/\/92it.top\/index.php?rest_route=\/wp\/v2\/posts\/4882"}],"collection":[{"href":"https:\/\/92it.top\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/92it.top\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/92it.top\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/92it.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=4882"}],"version-history":[{"count":1,"href":"https:\/\/92it.top\/index.php?rest_route=\/wp\/v2\/posts\/4882\/revisions"}],"predecessor-version":[{"id":4883,"href":"https:\/\/92it.top\/index.php?rest_route=\/wp\/v2\/posts\/4882\/revisions\/4883"}],"wp:attachment":[{"href":"https:\/\/92it.top\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=4882"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/92it.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=4882"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/92it.top\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=4882"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}