self.title = @"Your TiTle Text";
UILabel* tlabel=[[UILabel alloc] initWithFrame:CGRectMake(0,0, 200, 40)];
tlabel.text=self.navigationItem.title;
tlabel.textColor=[UIColor whiteColor];
tlabel.font = [UIFont fontWithName:@"Helvetica-Bold" size: 30.0];
tlabel.backgroundColor =[UIColor clearColor];
tlabel.adjustsFontSizeToFitWidth=YES;
self.navigationItem.titleView=tlabel;