[Learn HarmonyOS Next Knowledge Daily] Debugging, Network, Caching, Rich Text Editing, etc.

1. How to Use a Release Certificate for Debugging?

Since some functions require certificate information verification, debugging needs to be performed using both a debug certificate and a release certificate. However, after using the release certificate, an installation error occurs:

05/14 19:04:39: Install Failed: error: failed to install bundle.code:9568322error: signature verification failed due to not trusted app source.View detailed instructions.$ hdc shell rm -rf data/local/tmp/c07053e4cafe4f06bbbfecc3c2a697bbError while Deploy Hap.

Specification Issue: Release certificates published on the AppGallery cannot be installed through non-AppGallery channels.

Solution: For testing release certificate applications, consider using AGC->Open Testing.

2. Is netBearType Defined as an Array Type in the Documentation the Current Specification?

In scenarios where both Wi-Fi and cellular networks are connected (dual-mode), the netBearType parameter only returns the status information of Wi-Fi. The array type definition is the current specification to handle multiple calling scenarios.

3. How to Make RichEditor and a Component a Whole for Adaptive Scrolling Based on Cursor Position?

There is a Component above RichEditor, and the goal is to make RichEditor and the Component a whole that can scroll adaptively based on the cursor position. Currently, using a Scroller cannot obtain the specific coordinates of the cursor in RichEditor (cursor x and y positions relative to RichEditor), making scrolling impossible.

Solution: Wrap RichEditor and the Component with a Scroll component. Use the onAreaChange callback to call scroller.scrollBy to adjust the height of the scrolling component.

Reference Code:

@Entry
@Component
struct Index {
  editorController = new RichEditorController()
  scroller: Scroller = new Scroller()

  build() {
    Column() {
      Scroll(this.scroller) {
        Column() {
          Image($r('app.media.startIcon'))
            .width('100%')
            .height(200)
            .margin({ bottom: 20 })
          RichEditor({ controller: this.editorController })
            .id('RichEditor')
            .width('100%')
            .backgroundColor(Color.Yellow)
            .onReady(() => {
              this.editorController.addImageSpan($r("app.media.startIcon"),
                {
                  imageStyle:
                  {
                    size: ["100px", "100px"]
                  }
                })
              this.editorController.addTextSpan('男生女生向前冲',
                {
                  style:
                  {
                    fontColor: Color.Blue,
                    fontSize: 30
                  }
                })
            })
            .onAreaChange((_, value) => {
              if (_.height !== value.height) {
                this.scroller.scrollBy(0, Number(value.height) - 200)
                console.log('---_.height', _.height)
                console.log('---value.height', value.height)
              }
            })
          Button('getSpans-文字').onClick((event: ClickEvent) => {
            let getSpans = this.editorController.getSpans({ start: 0 })
            console.log('getSpans0' + JSON.stringify(getSpans[0]))
            // Strong casting is required to obtain text or image information
            let span0 = getSpans[0] as RichEditorTextSpanResult
            console.log('Text-related information: ' + JSON.stringify(span0))
          })
          Button('getSpans-图片').onClick((event: ClickEvent) => {
            let getSpans = this.editorController.getSpans({ start: 0 })
            console.log('getSpans1' + JSON.stringify(getSpans[1]))
            let span1 = getSpans[1] as RichEditorImageSpanResult
            console.log('Image-related information: ' + JSON.stringify(span1))
          })
          Button('RichEditor获焦').onClick(() => {
            focusControl.requestFocus('RichEditor')
          })
        }
      }
      .scrollable(ScrollDirection.Vertical) // Vertical scrolling direction
      .scrollBar(BarState.On) // Scrollbar always visible
      .scrollBarColor(Color.Gray) // Scrollbar color
    }
  }
}

4. Why Do Performance Issues Occur When Storing Complex Objects in LocalStorage or APPStorage?

Two questions about performance issues when storing complex objects in LocalStorage and APPStorage:

1. Frequent Reading/Writing: Why does frequent reading/writing of complex objects degrade page performance? Does LocalStorage affect page rendering?
2. Data Structure: Are data stored locally in LocalStorage and APPStorage? They should be in memory—why does serialization/deserialization occur?

Answers:

• LocalStorage operations are synchronous. When reading/writing, the program blocks until the operation completes, which affects refresh efficiency, especially for complex objects.
• LocalStorage and APPStorage do not serialize complex objects when reading them locally.

5. Error When Using Synchronous Methods to Get Network Status in a No-Network Environment?

In a no-network environment, calling synchronous methods cannot parse the corresponding nethandle content, and an error occurs when the method internally executes getCap. Use try-catch to get the error information:

try {
  let netHandle = connection.getDefaultNetSync();
  let connectionproperties = connection.getConnectionPropertiesSync(netHandle);
} catch(err) {
  console.info('error: ' + JSON.stringify(err));
}