HarmonyOS 鸿蒙Next TextInput空内容提示及问题四、五解答求助

import { hilog } from '[@kit](/user/kit).PerformanceAnalysisKit'
import { promptAction } from '[@kit](/user/kit).ArkUI';

[@Entry](/user/Entry)
[@ComponentV2](/user/ComponentV2)
struct Index {
  [@Local](/user/Local) list: Todo[] = []
  [@Local](/user/Local) todoInput: string = ''

  build() {
    Column() {
      Row() {
        TextInput({ text: $$this.todoInput })
          .layoutWeight(1)
        Button('添加').onClick(() => {
          if (this.todoInput.length == 0) {
            promptAction.showToast({
              message: '请输入'
            })
            return
          }
          this.list.push(new Todo(this.todoInput))
          this.todoInput = ''
        }).layoutWeight(0)

      }

      Scroll() {
        Column() {
          ForEach(this.list, (item: Todo, index: number) => {
            Row() {
              Text((index + 1).toString())
                .margin({ left: '8vp', right: '16vp' })
                .fontColor(item.isSelect ? Color.Red : Color.Black)
              Text(item.content)
                .fontColor(item.isSelect ? Color.Red : Color.Black)
                .backgroundColor(item.isSelect ? Color.Gray : Color.Pink)
                .padding('16vp')
              Blank()
              Button('删除').onClick(() => {
                promptAction.showDialog({
                  title: '删？', buttons: [{
                    text: '取消',
                    color: '0x000000'
                  },
                    {
                      text: '确定',
                      color: '0x000000'
                    }
                  ]
                }, (err, data) => {
                  if (data.index == 1) {
                    let list: Todo[] = []
                    this.list.forEach((it: Todo) => {
                      if (it != item) {
                        list.push(it)
                      }
                    })
                    this.list = list
                  }
                })
              })
            }
            .width('calc(100% - 8vp)')
            .margin({ top: '16vp' })
            .backgroundColor(item.isSelect ? Color.Gray : Color.Pink)
            .onClick(() => {
              item.isSelect = !item.isSelect
            })
          })
        }
      }.width('100%')
      .scrollBar(BarState.Off)
    }.size({ width: '100%', height: '100%' })
  }
}

[@ObservedV2](/user/ObservedV2)
class Todo {
  [@Trace](/user/Trace) isSelect: boolean = false
  content: string

  constructor(content: string = '') {
    this.content = content
  }
}