小编Kis*_*har的帖子

在react-native run-ios模拟器上使用其显示错误启动应用程序Unable to find module for EventDispatcher

我等了很长时间,但我的游乐场项目没有显示右侧栏上的结果我正在使用正确的代码但仍然正确的栏没有更新我不知道我尝试了很多时间是什么问题.这是我的代码

var str = "Hello, playground"

var str1 = "this is my first program"

let kermit = "kermit"
let msPiggy = "ms. piggy"

let string1 =  msPiggy + " and " + kermit + ", sitting in a tree"
let string2 = "\(msPiggy) and \(kermit), sittting in a tree "

let string3 = " kermit has \(5*2) fingers"

let  chr1:Character = ""

我已经检查了Xcode 9文档中的新内容,我发现了这一点

但我不明白为什么我可以用新的Xcode 9来使用它

我正在使用此代码来显示带有URL的图像

的.xaml

    <?xml version="1.0" encoding="UTF-8"?>
    <ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" x:Class="LandAHand.VolunteerView">
        <ContentPage.Content>
             <AbsoluteLayout BackgroundColor="Maroon">
                 <Image x:Name="backgroundImage" AbsoluteLayout.LayoutBounds="0,0,1,1"   AbsoluteLayout.LayoutFlags="All" HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand" Aspect="AspectFill"/>
             </AbsoluteLayout>
        </ContentPage.Content>
    </ContentPage>

的.cs

using System;
using System.Collections.Generic;

using Xamarin.Forms;

namespace LandAHand
{
    public partial class VolunteerView : ContentPage
    {
        public VolunteerView()
        {
            InitializeComponent();
            backgroundImage.Source = new UriImageSource
            {
                Uri = new Uri("https://s9.postimg.org/aq1jt3fu7/handshake_87122244_std.jpg"),
                CachingEnabled = true,
                CacheValidity = new TimeSpan(5, 0, 0, 0)
            };
        }
    }
}

此代码成功使用iOS但不使用android.

我想从上获取数据 viewWillAppear(_:)

是否有任何等于方法或修改现有SwiftUI 也是任何改良剂viewDidDisappear(_:)

如何List使用 Swift UI删除空行这是我的代码。

struct LandMarkList: View {
    var body: some View {
        NavigationView {
            List(LandMarkListData) { landmark in
                LandMarkRow(landmark: landmark)
            }

        .navigationBarTitle("List")
        }
    }
}

我在List里面添加了一个，ScorllView但是在添加到里面后它没有显示在画布中ScrollView

这是我的代码

struct ContentView: View {
    var body: some View {
        ScrollView {
            VStack {
                Text("My List")
                    .font(.largeTitle)
                    .fontWeight(.bold)

                List(0 ..< 5) { item in
                    Text("Hello World")
                }
            }
        }
    }
}

我正在使用 WebCrypto 库来解密数据，但它在 iOS 15 上不起作用，在 iOS 14 上工作正常

我检查过 webView 的评估JavaScript函数抛出错误

Error Domain=WKErrorDomain Code=4 "A JavaScript exception occurred" UserInfo={WKJavaScriptExceptionLineNumber=27, 
WKJavaScriptExceptionMessage=TypeError: undefined is not an object (evaluating 'y.importKey'), WKJavaScriptExceptionColumnNumber=8260, 
WKJavaScriptExceptionSourceURL=undefined, NSLocalizedDescription=A JavaScript exception occurred}

这是我在xcode 9游乐场的代码

class Tutorial: Codable {
    let title: String
    let author: String
    let editor: String
    let type: String
    let publishDate: Date

    init(title: String, author: String, editor: String, type: String, publishDate: Date) {
        self.title = title
        self.author = author
        self.editor = editor
        self.type = type
        self.publishDate = publishDate
    }
}

显示错误使用未声明类型'Date'

在由苹果arkit示例代码我得到类型(又名"阵列")的"[vector_float3]"这个误差值没有构件"高级",它正在与细9的XCode beta版或GM版本

我正在使用此代码

func hitTestWithFeatures(_ point: CGPoint, coneOpeningAngleInDegrees: Float,
                             minDistance: Float = 0,
                             maxDistance: Float = Float.greatestFiniteMagnitude,
                             maxResults: Int = 1) -> [FeatureHitTestResult] {

        var results = [FeatureHitTestResult]()

        guard let features = self.session.currentFrame?.rawFeaturePoints else {
            return results
        }

        guard let ray = hitTestRayFromScreenPos(point) else {
            return results
        }

        let maxAngleInDeg = min(coneOpeningAngleInDegrees, 360) / 2
        let maxAngle = ((maxAngleInDeg / 180) * Float.pi)

        let points = features.points

        for i in 0...features.__count {

            let feature = points.advanced(by: Int(i))
            let featurePos = …