Screen orientation issue in ios

I want to lock one of my page to landscape mode it works perfect in android but not in ios i can not rotate to landscape it still in portrait mode. do i have to change anything in xcode settings. i do not know what happened exactly. can you please get me out from this.

I have used something like this.

ionViewDidLoad() {
 this.screenOrientation.lock('landscape');
}

try this.screenOrientation.lock(this.screenOrientation.ORIENTATIONS.LANDSCAPE);