ionic4默认不能使用手势事件，解决方法

npm install hammerjs --save

import { enableProdMode } from ‘@angular/core‘;

import { platformBrowserDynamic } from ‘@angular/platform-browser-dynamic‘;

import { AppModule } from ‘./app/app.module‘;

import { environment } from ‘./environments/environment‘;

import ‘hammerjs‘;

if (environment.production) {

  enableProdMode();

}

platformBrowserDynamic().bootstrapModule(AppModule)

  .catch(err => console.log(err));