全局设置Nav的返回按钮以及滑动pop控制器

这篇文章写的是关于全局设置

按钮问题，以及左滑Pop控制器的问题

<ol>
<li> 当Push控制器的时候都会执行Nav的push 方法，那么我 们从写这个方法，利用传递进来的控制器给相对应的控制器设置返回导航，</li>
<li>与此同时当修改了Nav的返回按钮，它的左滑Pop就会失效，需要我们重设代理，执行相应代理来恢复它</li>

</ol>

@interface XMGNavigationController () <UIGestureRecognizerDelegate>

@end

@implementation XMGNavigationController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    
    self.interactivePopGestureRecognizer.delegate = self;
    
    [self.navigationBar setBackgroundImage:[UIImage imageNamed:@"navigationbarBackgroundWhite"] forBarMetrics:UIBarMetricsDefault];
}

/**
 *  重写push方法的目的 : 拦截所有push进来的子控制器
 *
 *  @param viewController 刚刚push进来的子控制器
 */
- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated
{
    if (self.childViewControllers.count > 0) { // 如果viewController不是最早push进来的子控制器
        // 左上角
        UIButton *backButton = [UIButton buttonWithType:UIButtonTypeCustom];
        [backButton setImage:[UIImage imageNamed:@"navigationButtonReturn"] forState:UIControlStateNormal];
        [backButton setImage:[UIImage imageNamed:@"navigationButtonReturnClick"] forState:UIControlStateHighlighted];
        [backButton setTitle:@"返回" forState:UIControlStateNormal];
        [backButton setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
        [backButton setTitleColor:[UIColor redColor] forState:UIControlStateHighlighted];
        [backButton sizeToFit];
        // 这句代码放在sizeToFit后面
        backButton.contentEdgeInsets = UIEdgeInsetsMake(0, -20, 0, 0);
        [backButton addTarget:self action:@selector(back) forControlEvents:UIControlEventTouchUpInside];
        viewController.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:backButton];
        
        // 隐藏底部的工具条
        viewController.hidesBottomBarWhenPushed = YES;
    }
    
    // 所有设置搞定后, 再push控制器
    [super pushViewController:viewController animated:animated];
}

- (void)back
{
    [self popViewControllerAnimated:YES];
}

#pragma mark - <UIGestureRecognizerDelegate>
/**
 *  手势识别器对象会调用这个代理方法来决定手势是否有效
 *
 *  @return YES : 手势有效, NO : 手势无效
 */
- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer
{

    
    // 手势何时有效 : 当导航控制器的子控制器个数 > 1就有效
    return self.childViewControllers.count > 1;
}