{"id":301313,"date":"2020-04-05T15:00:21","date_gmt":"2020-04-05T15:00:21","guid":{"rendered":"http:\/\/savepearlharbor.com\/?p=301313"},"modified":"-0001-11-30T00:00:00","modified_gmt":"2020-04-05T15:00:21","slug":"","status":"publish","type":"post","link":"https:\/\/savepearlharbor.com\/?p=301313","title":{"rendered":"\u0424\u043e\u0440\u043c\u0438\u0440\u0443\u0435\u043c View \u0432 SwiftUI, \u0438\u0441\u0445\u043e\u0434\u044f \u0438\u0437 \u0443\u0441\u043b\u043e\u0432\u0438\u0439"},"content":{"rendered":"\n<div class=\"post__text post__text-html post__text_v1\" id=\"post-content-body\" data-io-article-url=\"https:\/\/habr.com\/ru\/post\/495746\/\">\u0418\u043d\u043e\u0433\u0434\u0430 \u043d\u0430\u043c \u043d\u0443\u0436\u043d\u043e \u0441\u0444\u043e\u0440\u043c\u0438\u0440\u043e\u0432\u0430\u0442\u044c SwiftUI View, \u0443\u0447\u0438\u0442\u044b\u0432\u0430\u044f \u043d\u0435\u043a\u043e\u0442\u043e\u0440\u044b\u0435 \u0443\u0441\u043b\u043e\u0432\u0438\u044f. \u041d\u0430\u043f\u0440\u0438\u043c\u0435\u0440, \u0432 \u043f\u0440\u0438\u0432\u0435\u0434\u0435\u043d\u043d\u043e\u043c \u043a\u043e\u0434\u0435 \u043c\u044b \u043e\u043f\u0440\u0435\u0434\u0435\u043b\u044f\u0435\u043c <b>HomeView<\/b>, \u043a\u043e\u0442\u043e\u0440\u044b\u0439 \u043c\u043e\u0436\u0435\u0442 \u0441\u043e\u0434\u0435\u0440\u0436\u0430\u0442\u044c <b>ProfileView<\/b>, \u0432 \u0441\u043b\u0443\u0447\u0430\u0435 \u0435\u0441\u043b\u0438 \u0432 <b>LogInManager<\/b> \u0435\u0441\u0442\u044c <b>loggedInUser<\/b>. \u041c\u044b \u043f\u044b\u0442\u0430\u0435\u043c\u0441\u044f \u044d\u0442\u043e \u0440\u0435\u0430\u043b\u0438\u0437\u043e\u0432\u0430\u0442\u044c, \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u0443\u044f \u0441\u0442\u0430\u043d\u0434\u0430\u0440\u0442\u043d\u044b\u0439 \u043e\u043f\u0435\u0440\u0430\u0442\u043e\u0440 if:<br \/>  <a name=\"habracut\"><\/a>  <\/p>\n<pre><code class=\"swift\">struct HomeView: View {     @ObservedObject var loginManager: LoginManager      var body: some View {         VStack {             if let user = loginManager.loggedInUser {                 ProfileView(user: user)             }              ...         }     } }<\/code><\/pre>\n<p>  \u041a \u0441\u043e\u0436\u0430\u043b\u0435\u043d\u0438\u044e, \u044d\u0442\u043e\u0442 \u043a\u043e\u0434 \u0432\u044b\u0434\u0430\u0441\u0442 \u043f\u0440\u0438 \u043a\u043e\u043c\u043f\u0438\u043b\u044f\u0446\u0438\u0438 \u043e\u0448\u0438\u0431\u043a\u0443:  <\/p>\n<blockquote><p>Closure containing control flow statement cannot be used with function builder ViewBuilder.<\/p><\/blockquote>\n<p>  \u0422\u0430\u043a \u043a\u0430\u043a \u0437\u0434\u0435\u0441\u044c \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u0443\u044e\u0442\u0441\u044f \u043d\u0435 \u043e\u0431\u044b\u0447\u043d\u044b\u0435 \u0437\u0430\u043c\u044b\u043a\u0430\u043d\u0438\u044f, \u0430 <b>function builders<\/b>, \u043c\u044b \u043d\u0435 \u043c\u043e\u0436\u0435\u043c \u043f\u043e\u043c\u0435\u0441\u0442\u0438\u0442\u044c \u0432 \u043d\u0438\u0445 \u043f\u0440\u043e\u0438\u0437\u0432\u043e\u043b\u044c\u043d\u044b\u0439 \u043a\u043e\u0434 \u0434\u043b\u044f \u0444\u043e\u0440\u043c\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u044f HStack \u0438\u043b\u0438 VStack. \u0422\u0430\u043a \u043a\u0430\u043a \u0436\u0435 \u043d\u0430\u043c \u0432\u044b\u0439\u0442\u0438 \u0438\u0437 \u043f\u043e\u043b\u043e\u0436\u0435\u043d\u0438\u044f?<\/p>\n<p>  \u041e\u0434\u0438\u043d \u0438\u0437 \u0441\u043f\u043e\u0441\u043e\u0431\u043e\u0432 \u2014 \u043f\u0435\u0440\u0435\u0434\u0430\u0442\u044c \u043e\u0431\u0440\u0430\u0431\u043e\u0442\u043a\u0443 \u0442\u0430\u043a\u0438\u0445 optionals \u043d\u0435\u043f\u043e\u0441\u0440\u0435\u0434\u0441\u0442\u0432\u0435\u043d\u043d\u043e \u0432 \u0442\u0435 view, \u043a\u043e\u0442\u043e\u0440\u044b\u0435 \u043c\u044b \u0444\u043e\u0440\u043c\u0438\u0440\u0443\u0435\u043c. \u041d\u0430\u043f\u0440\u0438\u043c\u0435\u0440, \u043c\u044b \u043c\u043e\u0436\u0435\u043c \u043f\u0435\u0440\u0435\u0434\u0430\u0432\u0430\u0442\u044c \u0432 \u043d\u0430\u0448 ProfileView \u043d\u0435 \u043a\u043e\u043d\u043a\u0440\u0435\u0442\u043d\u043e\u0435 \u0437\u043d\u0430\u0447\u0435\u043d\u0438\u0435 User, \u0430 \u0441\u0434\u0435\u043b\u0430\u0442\u044c \u0435\u0433\u043e optional:<\/p>\n<pre><code class=\"swift\">struct ProfileView: View {     var user: User?      var body: some View {         guard let user = user else {             \/\/ We have to use 'AnyView' to perform type erasure here,             \/\/ in order to give our 'body' a single return type:             return AnyView(EmptyView())         }          return AnyView(VStack {             Text(user.name)             ...         })     } }<\/code><\/pre>\n<p>  \u042d\u0442\u043e\u0442 \u043a\u043e\u0434 \u0440\u0430\u0431\u043e\u0442\u0430\u0435\u0442, \u043d\u043e \u043d\u0435 \u043e\u0441\u043e\u0431\u043e \u043a\u0440\u0430\u0441\u0438\u0432. \u041d\u0435\u0442 \u043d\u0438\u043a\u0430\u043a\u043e\u0433\u043e \u0441\u043c\u044b\u0441\u043b\u0430 \u0441\u043e\u0437\u0434\u0430\u0432\u0430\u0442\u044c ProfileView \u0434\u043b\u044f \u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u0442\u0435\u043b\u044f nil. \u041f\u0440\u0438\u043c\u0435\u043d\u0438\u043c \u0434\u0440\u0443\u0433\u043e\u0439 \u043f\u043e\u0434\u0445\u043e\u0434: \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u0443\u0435\u043c <b>map<\/b> \u043a \u043d\u0430\u0448\u0435\u043c\u0443 optional User, \u0447\u0442\u043e\u0431\u044b \u043f\u0440\u0435\u043e\u0431\u0440\u0430\u0437\u043e\u0432\u0430\u0442\u044c \u0435\u0433\u043e \u0432 ProfileView:<\/p>\n<pre><code class=\"swift\">struct HomeView: View {     @ObservedObject var loginManager: LoginManager      var body: some View {         VStack {             loginManager.loggedInUser.map { user in                 ProfileView(user: user)             }             ...         }     } }<\/code><\/pre>\n<p>  \u0422\u0430\u043a \u0443\u0436\u0435 \u0433\u043e\u0440\u0430\u0437\u0434\u043e \u0441\u0438\u043c\u043f\u0430\u0442\u0438\u0447\u043d\u0435\u0435: \u043d\u0430\u043c \u043d\u0435 \u043d\u0443\u0436\u043d\u043e \u0432\u0440\u0443\u0447\u043d\u0443\u044e \u043e\u0442\u0434\u0430\u0432\u0430\u0442\u044c EmptyView, \u043a\u043e\u0433\u0434\u0430 \u0443 User \u043e\u0442\u0441\u0443\u0442\u0441\u0442\u0432\u0443\u0435\u0442 \u0437\u043d\u0430\u0447\u0435\u043d\u0438\u0435. \u0422\u0430\u043a\u0436\u0435 \u043c\u044b \u043e\u043f\u044f\u0442\u044c \u043c\u043e\u0436\u0435\u043c \u043f\u0435\u0440\u0435\u0434\u0430\u0432\u0430\u0442\u044c \u0432 ProfileView \u043a\u043e\u043d\u043a\u0440\u0435\u0442\u043d\u043e\u0435 \u0437\u043d\u0430\u0447\u0435\u043d\u0438\u0435, \u0430 \u043d\u0435 optional. \u0410 \u043c\u043e\u0436\u043d\u043e \u043b\u0438 \u0441\u0434\u0435\u043b\u0430\u0442\u044c \u0435\u0449\u0451 \u043b\u0443\u0447\u0448\u0435?<\/p>\n<p>  \u0425\u043e\u0440\u043e\u0448\u0430\u044f \u043d\u043e\u0432\u043e\u0441\u0442\u044c \u043e <b>@ViewBuilder<\/b> \u0441\u043e\u0441\u0442\u043e\u0438\u0442 \u0432 \u0442\u043e\u043c, \u0447\u0442\u043e \u044d\u0442\u043e \u043d\u0435 \u043a\u0430\u043a\u0430\u044f-\u0442\u043e \u0437\u0430\u043a\u0440\u044b\u0442\u0430\u044f \u0440\u0435\u0430\u043b\u0438\u0437\u0430\u0446\u0438\u044f \u0432 SwiftUI, \u0430 \u0434\u043e\u0441\u0442\u0443\u043f\u043d\u044b\u0439 \u0430\u0442\u0440\u0438\u0431\u0443\u0442, \u043a\u043e\u0442\u043e\u0440\u044b\u043c \u043c\u044b \u043c\u043e\u0436\u0435\u043c \u0430\u043d\u043d\u043e\u0442\u0438\u0440\u043e\u0432\u0430\u0442\u044c \u0441\u0432\u043e\u0438 \u0441\u043e\u0431\u0441\u0442\u0432\u0435\u043d\u043d\u044b\u0435 \u0444\u0443\u043d\u043a\u0446\u0438\u0438 \u0438 \u0437\u0430\u043c\u044b\u043a\u0430\u043d\u0438\u044f.<\/p>\n<p>  \u0418\u0441\u043f\u043e\u043b\u044c\u0437\u0443\u044f \u044d\u0442\u043e\u0442 \u0430\u0442\u0440\u0438\u0431\u0443\u0442 \u043c\u044b \u043c\u043e\u0436\u0435\u043c \u0441\u043e\u0431\u0440\u0430\u0442\u044c view Unwrap, \u043a\u043e\u0442\u043e\u0440\u044b\u0439 \u043f\u0440\u0438\u043d\u0438\u043c\u0430\u0435\u0442 \u0432 \u043a\u0430\u0447\u0435\u0441\u0442\u0432\u0435 \u043f\u0430\u0440\u0430\u043c\u0435\u0442\u0440\u043e\u0432 optional \u0437\u043d\u0430\u0447\u0435\u043d\u0438\u0435 \u0438 \u043f\u043e\u043c\u0435\u0447\u0435\u043d\u043d\u0443\u044e <b>@ViewBuilder<\/b> \u0437\u0430\u043c\u044b\u043a\u0430\u043d\u0438\u0435 \u0434\u043b\u044f \u043f\u0440\u0435\u043e\u0431\u0440\u0430\u0437\u043e\u0432\u0430\u043d\u0438\u044f \u043d\u0435-nil \u0437\u043d\u0430\u0447\u0435\u043d\u0438\u044f \u0432\u043e View:<\/p>\n<pre><code class=\"swift\">struct Unwrap&lt;Value, Content: View&gt;: View {     private let value: Value?     private let contentProvider: (Value) -&gt; Content      init(_ value: Value?,          @ViewBuilder content: @escaping (Value) -&gt; Content) {         self.value = value         self.contentProvider = content     }      var body: some View {         value.map(contentProvider)     } }<\/code><\/pre>\n<p>  \u0418\u0441\u043f\u043e\u043b\u044c\u0437\u0443\u044f \u044d\u0442\u0443 \u043a\u043e\u043d\u0441\u0442\u0440\u0443\u043a\u0446\u0438\u044e, \u043c\u044b \u0442\u0435\u043f\u0435\u0440\u044c \u043c\u043e\u0436\u0435\u043c \u043f\u043e\u043b\u043d\u043e\u0441\u0442\u044c\u044e \u043f\u0435\u0440\u0435\u0440\u0430\u0431\u043e\u0442\u0430\u0442\u044c \u0432\u0441\u044e \u0441\u0442\u0440\u0443\u043a\u0442\u0443\u0440\u0443 HomeView:<\/p>\n<pre><code class=\"swift\">struct HomeView: View {     @ObservedObject var loginManager: LoginManager      var body: some View {         VStack {             Unwrap(loginManager.loggedInUser) { user in                 HStack {                     Text(&quot;Logged in as:&quot;)                     ProfileView(user: user)                 }             }             ...         }     } } <\/code><\/pre>\n<\/div>\n<p> \u0441\u0441\u044b\u043b\u043a\u0430 \u043d\u0430 \u043e\u0440\u0438\u0433\u0438\u043d\u0430\u043b \u0441\u0442\u0430\u0442\u044c\u0438 <a href=\"https:\/\/habr.com\/ru\/post\/495746\/\"> https:\/\/habr.com\/ru\/post\/495746\/<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"\n<div class=\"post__text post__text-html post__text_v1\" id=\"post-content-body\" data-io-article-url=\"https:\/\/habr.com\/ru\/post\/495746\/\">\u0418\u043d\u043e\u0433\u0434\u0430 \u043d\u0430\u043c \u043d\u0443\u0436\u043d\u043e \u0441\u0444\u043e\u0440\u043c\u0438\u0440\u043e\u0432\u0430\u0442\u044c SwiftUI View, \u0443\u0447\u0438\u0442\u044b\u0432\u0430\u044f \u043d\u0435\u043a\u043e\u0442\u043e\u0440\u044b\u0435 \u0443\u0441\u043b\u043e\u0432\u0438\u044f. \u041d\u0430\u043f\u0440\u0438\u043c\u0435\u0440, \u0432 \u043f\u0440\u0438\u0432\u0435\u0434\u0435\u043d\u043d\u043e\u043c \u043a\u043e\u0434\u0435 \u043c\u044b \u043e\u043f\u0440\u0435\u0434\u0435\u043b\u044f\u0435\u043c <b>HomeView<\/b>, \u043a\u043e\u0442\u043e\u0440\u044b\u0439 \u043c\u043e\u0436\u0435\u0442 \u0441\u043e\u0434\u0435\u0440\u0436\u0430\u0442\u044c <b>ProfileView<\/b>, \u0432 \u0441\u043b\u0443\u0447\u0430\u0435 \u0435\u0441\u043b\u0438 \u0432 <b>LogInManager<\/b> \u0435\u0441\u0442\u044c <b>loggedInUser<\/b>. \u041c\u044b \u043f\u044b\u0442\u0430\u0435\u043c\u0441\u044f \u044d\u0442\u043e \u0440\u0435\u0430\u043b\u0438\u0437\u043e\u0432\u0430\u0442\u044c, \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u0443\u044f \u0441\u0442\u0430\u043d\u0434\u0430\u0440\u0442\u043d\u044b\u0439 \u043e\u043f\u0435\u0440\u0430\u0442\u043e\u0440 if:  <\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[],"tags":[],"class_list":["post-301313","post","type-post","status-publish","format-standard","hentry"],"_links":{"self":[{"href":"https:\/\/savepearlharbor.com\/index.php?rest_route=\/wp\/v2\/posts\/301313","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/savepearlharbor.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/savepearlharbor.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/savepearlharbor.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/savepearlharbor.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=301313"}],"version-history":[{"count":0,"href":"https:\/\/savepearlharbor.com\/index.php?rest_route=\/wp\/v2\/posts\/301313\/revisions"}],"wp:attachment":[{"href":"https:\/\/savepearlharbor.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=301313"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/savepearlharbor.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=301313"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/savepearlharbor.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=301313"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}