Directive for NativeScript-angular, adding the property maxLines to Label

label-max-lines.directive.ts

import { Directive, ElementRef, Input, OnInit, OnChanges } from '@angular/core';
import { Label } from 'ui/label';

@Directive({
  selector: '[maxLines]',
})
export class LabelMaxLinesDirective implements OnInit, OnChanges {
  @Input('maxLines') public maxLines: number = 1;

  public get nativeView(): Label {
    return this.el.nativeElement;
  }

  constructor(private el: ElementRef) {}

  public ngOnInit() {
    const nativeView = this.nativeView;

    if (nativeView instanceof Label) {
      nativeView.on(Label.loadedEvent, () => {
        this.applyMaxLines();
      });
    }
  }

  public ngOnChanges(changes: any) {
    if (changes.maxLines) {
      this.applyMaxLines();
    }
  }

  private applyMaxLines() {
    const nativeView = this.nativeView;

    const maxLines = Math.max(Number(this.maxLines) || 0, 1);

    if (nativeView.android) {
      nativeView.android.setMaxLines(maxLines);
    } else if (nativeView.ios) {
      nativeView.ios.numberOfLines = maxLines;
    }
  }
}