更改导航栏的标题

-(void)setTitle:(NSString *)title{

   UILabel *titlelabel = [[UILabelalloc] initWithFrame:CGRectZero];

    titlelabel.textColor= [UIColorblackColor];

    titlelabel.font = [UIFontsystemFontOfSize:18.0f];

    titlelabel.backgroundColor=[UIColorclearColor];

    titlelabel.text=title;

    [titlelabelsizeToFit];

    

    self.navigationItem.titleView=titlelabel;

}