开启UIViewController向右滑动实现返回的功能

要屏蔽/开启某一个UIViewController的系统自带的右滑手势实现返回的功能。如下步骤：

（1）在.m文件中实现如下代码：（一般写在viewDidLoad方法中）

- (void)viewDidLoad {
    [super viewDidLoad];
    if ([[UIDevice currentDevice].systemVersion floatValue]>=7.0) {
        if ([self.navigationController respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
            self.navigationController.interactivePopGestureRecognizer.enabled = YES;
            self.navigationController.interactivePopGestureRecognizer.delegate = self;
        }  
    }  

}

（2）在此viewController的头文件中加入代理<UIGestureRecognizerDelegate>;

@interface BaseViewController ()<UIGestureRecognizerDelegate>

@end

（2）实现代理方法

- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer{
    if ([self.navigationController.viewControllers count] == 1) {
        return NO;
    }else{
        return YES;
    }
}