I want to do a pull refresh .but does not work my code.please anyone help me

ionic-v1
1

i want to do a pull refresh .but does not work my code.please anyone help me
Here my code:

doRefresh(refresher){
    this.http.get( this.url ) . subscribe ((data) => {
      this.items = data;
 
      if(refresher != 0)
         refresher.complete();
    });  
}