fix(datepicker): double tap ios issue (#5821)

src/datepicker/themes/bs/bs-days-calendar-view.component.ts

@@ -42,17 +42,21 @@ import { BsDatepickerConfig } from '../../bs-datepicker.config';
         <tbody>
         <tr *ngFor="let week of calendar.weeks; let i = index">
           <td class="week" [class.active-week]="isWeekHovered"  *ngIf="options.showWeekNumbers">
-            <span
+            <span *ngIf="isiOS" (click)="selectWeek(week)">{{ calendar.weekNumbers[i] }}</span>
+            <span *ngIf="!isiOS"
                 (click)="selectWeek(week)"
                 (mouseenter)="weekHoverHandler(week, true)"
                 (mouseleave)="weekHoverHandler(week, false)">{{ calendar.weekNumbers[i] }}</span>
           </td>
           <td *ngFor="let day of week.days" role="gridcell">
-          <span bsDatepickerDayDecorator
+          <span *ngIf="!isiOS" bsDatepickerDayDecorator
                 [day]="day"
                 (click)="selectDay(day)"
                 (mouseenter)="hoverDay(day, true)"
                 (mouseleave)="hoverDay(day, false)">{{ day.label }}</span>
+            <span *ngIf="isiOS" bsDatepickerDayDecorator
+                  [day]="day"
+                  (click)="selectDay(day)">{{ day.label }}</span>
           </td>
         </tr>
         </tbody>
@@ -73,8 +77,12 @@ export class BsDaysCalendarViewComponent  {
   @Output() onHoverWeek = new EventEmitter<WeekViewModel>();
 
   isWeekHovered: boolean;
+  isiOS: RegExpMatchArray;
 
-  constructor(private _config: BsDatepickerConfig) { }
+  constructor(private _config: BsDatepickerConfig) {
+    const device = navigator.userAgent.toLowerCase();
+    this.isiOS = device.match(/(iphone|ipod|ipad|apple)/);
+  }
 
   navigateTo(event: BsNavigationDirection): void {
     const step = BsNavigationDirection.DOWN === event ? -1 : 1;