从WatchOS捕获Apple Watch的型号标识符

如何解决从WatchOS捕获Apple Watch的型号标识符

似乎没有任何记录的官方方法可以从手表应用程序获取Apple Watch模型，但是这篇文章显示了sysctlbyname的特殊用法：

How to determine the Apple Watch model?

有人可以帮我弄清楚为什么此功能不起作用吗？有时会返回

“ Watc \ t”

而不是预期的

“ Watch2,4”

Swift的sysctlbyname函数似乎是这里描述的c函数： https://opensource.apple.com/source/Libc/Libc-167/gen.subproj/sysctlbyname.c.auto.html

我的代码是从SO帖子的快速答案中复制的：

private func getWatchModel() -> String? {
   var size: size_t = 0
   sysctlbyname("hw.machine",nil,&size,0)
   var machine = CChar()
   sysctlbyname("hw.machine",&machine,0)
   return String(cString: &machine,encoding: String.Encoding.utf8)?.trimmingCharacters(in: .whitespacesAndNewlines)
} // Should return a string like "Watch2,4"

解决方法

您永远不会分配缓冲区来接收机器字符串。 更改

var machine = [CChar](repeating: 0,count: size) 

到

import React,{ Component } from 'react';
import { Form,Button } from 'react-bootstrap';
import Items from './items'
import Navbar from './navbar'

class Home extends Component {
    constructor() {
        super();
        this.state = {
            value: 'enter',condimentCount: 5,menuItems: [
                {
                    "id": 1234,"item_name": 'chow mein',"category_id": 'meal'
                },{
                    "id": 1235,"item_name": '',"category_id": 'meal'
                }
            ]
        };
            this.handleCategory = this.handleCategory.bind(this);
    }



    handleCategory = (event,id) => {
        console.log('changing meal type',event.target.value)
        //this.setState({value: event.target.value});

        // 1. Make a shallow copy of the items
         let items = [...this.state.menuItems];
        // 2. Make a shallow copy of the item you want to mutate
         let item = {...items[0]};
        // 3. Replace the property you're intested in
         item.category_id = event.target.value;
        // 4. Put it back into our array. N.B. we *are* mutating the array here,but that's why we made a copy first
         items[0] = item;
        // 5. Set the state to our new copy
         this.setState({menuItems: items});
    }



    render() {

        let menuItems = null;
        if (this.state.menuItems) {
            menuItems = (
                <div>
                    {
                        this.state.menuItems.map((item,i) => {
                            return <div key={i}>
                                <MenuItem
                                    key={item.id} //IS THIS CORRECT?
                                    item_name={item.item_name}
                                    category_id={item.category_id}
                                    handleCategory={this.handleCategory}
                                />
                            </div>
                        })
                    }
                </div>
            )
        }

        return (

            <div>
                <Navbar />
                <div>
                    {Items}
                </div>


            </div>
        );
    }
}

export default Home;

你应该很好！