点击背景键盘退下

- (void)viewDidLoad
{
    [super viewDidLoad]; 
    [self addTapForView];

}

- (void)addTapForView {
    
    UITapGestureRecognizer *tapGestureRecognizer =[[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(backupgroupTap:)];
    tapGestureRecognizer.numberOfTapsRequired =1;
    [self.view addGestureRecognizer:tapGestureRecognizer];
    [tapGestureRecognizer setCancelsTouchesInView:NO];
}

-(void)backupgroupTap:(id)sender{
    [self.view endEditing:YES];
}