//添加返回按鈕-(void)backBtn{  UIButton *backBtn=[[UIButton alloc]initWithFrame:CGRectMake(0, 10, 60, 20)];  [backBtn setTitle:@"返回" forState:UIControlStateNormal];  backBtn.titleLabel.font=[UIFont systemFontOfSize:12];  backBtn.imageEdgeInsets=UIEdgeInsetsMake(2,2,2,2);  [backBtn setImage:[UIImage imageNamed:@"fanhui"] forState:UIControlStateNormal];  [backBtn addTarget:self action:@selector(backto) forControlEvents:UIControlEventTouchDown];  UIBarButtonItem *leftBtn=[[UIBarButtonItem alloc]initWithCustomView:backBtn];  UIBarButtonItem *flexBtn=[[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace target:nil action:nil];  flexBtn.width=-10;//正數(shù)往左移，負(fù)數(shù)往右移  self.navigationItem.leftBarButtonItems=@[flexBtn,leftBtn];}//返回按鈕-(void)backto{  [self dismissViewControllerAnimated:YES completion:^{  }];}