To remove the statusbar extra 20px definitely on iOS devices I followed this steps:
1- Add statusbarPadding: false to APP config and StatusBar.hide() on platform ready :
@App({
template: '<ion-nav id="nav" [root]="rootPage" #content swipeBackEnabled="false"></ion-nav>',
config: {
// removes statusbar padding
statusbarPadding: false
}
})
export class MyApp {
rootPage = YourHomePage;
constructor(platform:Platform) {
platform.ready().then(() => {
if (StatusBar) {
// hide StatusBar using cordova-plugin-statusbar
StatusBar.hide();
}
}
});
}
}
2- In xcode, set ‘View controller-based status bar…’ setting to “NO” inside ‘Build Settings’ tab:
3 - Check this two checkboxes in xcode (General tab):
- Hide during application launch.
- Requires full screen.

I solved this issue using this method @juanfsemaan.
