Currently, I am using the NativeScript framework along with the nativescript-bluetooth plugin to develop a BLE searching application. However, I am facing a challenge in updating the view while the device is being searched for. Below is the relevant code snippet:
app.modules.ts
import { NgModule, NO_ERRORS_SCHEMA } from "@angular/core";
import { NativeScriptModule } from "nativescript-angular/nativescript.module";
import { AppComponent } from "./app.component";
@NgModule({
declarations: [AppComponent],
bootstrap: [AppComponent],
imports: [NativeScriptModule],
schemas: [NO_ERRORS_SCHEMA],
})
export class AppModule {}
app.component.ts
import {Component} from "@angular/core";
let ble = require("nativescript-bluetooth");
@Component({
selector: "my-app",
styleUrls: ['app.css'],
templateUrl: "app.component.html"
})
export class AppComponent {
log: string = "";
startScanning() {
ble.startScanning({
serviceUUIDs: [],
seconds: 5,
onDiscovered: (peripheral) => {
if (peripheral.name == "SWING") {
this.stopScanning();
this.updateLog(`Device Name: ${peripheral.name}`);
}
}
}).then(() => {
this.updateLog("scanning completed");
}, (err) => {
console.error(`Error on scanning: ${err}`);
})
}
stopScanning() {
ble.stopScanning().then(() => {
this.updateLog("Stopped");
})
}
updateLog(message) {
console.log(message);
this.log += `\n${message}`;
}
}
app.component.html
<ActionBar title="My App">
</ActionBar>
<StackLayout>
<Button class="btn btn-primary btn-active" id="appButton" text="Search Device" (tap)="startScanning()"></Button>
<TextView text="{{ log }}" style="height: 100%;background-color: #282a37;color: #fff;" editable="false"></TextView>
</StackLayout>
Even though it is expected to display real-time updates in the log while scanning, there seems to be a delay of 5 seconds before it actually reflects the changes due to the completion of ble.startScanning. This issue might not be directly related to the BLE plugin but rather could point towards Javascript Promise and NativeScript peculiarities.
Your feedback would be highly appreciated.