iOS - 实现UINavigation全屏滑动返回(一)

/** 系统手势代理 */
@property(nonatomic, strong) id popGesture;

- (void)viewDidLoad {
 [super viewDidLoad];

  // 记录系统手势代理
  self.popGesture = self.interactivePopGestureRecognizer;
  self.delegate = self;
}

#pragma mark - UINavigationControllerDelegate
// 当控制器显示完毕的时候调用
- (void)navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animated {
    // 根据 栈 先进后出
    if (self.viewControllers[0] == viewController) { // 根控制器
        // 还原代理
        self.interactivePopGestureRecognizer.delegate = self.popGesture;
    } else { // 非控制器
        // 清空手势代理就能实现滑动返回，iOS6不支持
        self.interactivePopGestureRecognizer.delegate = nil;
    }
    // 如果当前控制器为根控制器，则使手势失效，不然手势会将根控制器移除
    if (self.viewControllers.count == 1) {
        self.interactivePopGestureRecognizer.enabled = NO;
    } else {
        self.interactivePopGestureRecognizer.enabled = YES;
    }
}