1.自定义返回按钮的同时, 保持iOS原生滑动返回手势(interactivePopGestureRecognizer)可用的方法
注意:
(1) 这样做会导致导航栏混乱, 即一个页面可能显示别的页面的导航栏, 甚至更严重的bug,效果如下:
(2) 如果只是单纯重设interactivePopGestureRecognizer的代理, 在push的过程中触发滑动返回会崩溃(好像还有别的问题), 所以需要在push动画过程中禁掉interactivePopGestureRecognizer手势

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//
//  SENavigationViewController.m
//  SpeakEnglish
//
//  Created by Daniel on 16/4/1.
//  Copyright © 2016年 Daniel. All rights reserved.
//

#import "SENavigationViewController.h"
#import "UIImage+ZY.h"

@interface SENavigationViewController ()<UIGestureRecognizerDelegate, UINavigationControllerDelegate>

@end

@implementation SENavigationViewController

- (instancetype)initWithRootViewController:(UIViewController *)rootViewController {
    if (self = [super initWithRootViewController:rootViewController]) {
        [self setNavigationBarTheme];
        self.delegate = self;
    }
    return self;
}


// 主题
- (void)setNavigationBarTheme {
    
    // title属性
    UINavigationBar *bar = [UINavigationBar appearance];
    NSDictionary *attr = @{NSForegroundColorAttributeName:[UIColor whiteColor],
                           NSFontAttributeName:FontTitle};
    [bar setTitleTextAttributes:attr];
    
    // 背景颜色
    [bar setBackgroundImage:[UIImage createImageWithColor:HEXCOLORV(ColorMain)] forBarMetrics:UIBarMetricsDefault];
    [bar setShadowImage:[UIImage createImageWithColor:HEXCOLORV(ColorMain)]];
    
    
    // 按钮图片渲染
    [bar setTintColor:[UIColor whiteColor]];
    
    // 按钮属性
    UIBarButtonItem *item = [UIBarButtonItem appearance];
    NSDictionary *itemAttr = @{NSForegroundColorAttributeName:[UIColor whiteColor],NSFontAttributeName:[UIFont systemFontOfSize:16]};
    [item setTitleTextAttributes:itemAttr forState:UIControlStateNormal];
    [item setTintColor:[UIColor whiteColor]];
}

- (void)viewDidLoad {
    [super viewDidLoad];
    
    // 自定义返回键(leftItem)后, 滑动返回不可用, 使用这种方式处理
    __weak typeof (self) weakSelf = self;
    if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
        self.interactivePopGestureRecognizer.delegate = weakSelf;
    }
}

- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated {
    
    // 禁用返回手势, 防止崩溃
    if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
        self.interactivePopGestureRecognizer.enabled = NO;
    }
    
    // 隐藏tabBar
    if (self.viewControllers.count == 1) {
        viewController.hidesBottomBarWhenPushed = YES;
    }
    
    // 定制返回键
    if (self.viewControllers.count >= 1) {
        UIButton *btn = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 60, 20)];
        
        [btn setImage:[UIImage templateImageWithName:@"nav_back"] forState:UIControlStateNormal];
        [btn.imageView setContentMode:UIViewContentModeScaleAspectFit];
        [btn setImageEdgeInsets:UIEdgeInsetsMake(0, -50, 0, 0)];
        
        [btn addTarget:self action:@selector(popSelector) forControlEvents:UIControlEventTouchUpInside];
        btn.tintColor = [UIColor whiteColor];
        
        UIBarButtonItem *item = [[UIBarButtonItem alloc] initWithCustomView:btn];
        viewController.navigationItem.leftBarButtonItem = item;
    }
    
    [super pushViewController:viewController animated:animated];
}

// 返回手势可用
- (void)navigationController:(UINavigationController *)navigationController
       didShowViewController:(UIViewController *)viewController
                    animated:(BOOL)animated {
    if ([navigationController respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
        navigationController.interactivePopGestureRecognizer.enabled = YES;
    }
}

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

- (UIStatusBarStyle)preferredStatusBarStyle {
    return self.visibleViewController.preferredStatusBarStyle;
}


- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
}

@end

2. '更换返回按钮箭头并去掉返回按钮文字'的方法, 这样不会出现奇怪的bug,
   缺点:
   (1). 是返回按钮样式自由度不够高
   (2). 隐藏导航栏后, 滑动返回不可用

//
//  SENavigationViewController.m
//  SpeakEnglish
//
//  Created by Daniel on 16/4/1.
//  Copyright © 2016年 Daniel. All rights reserved.
//

#import "SENavigationViewController.h"
#import "UIImage+ZY.h"

@interface SENavigationViewController ()<UIGestureRecognizerDelegate, UINavigationControllerDelegate>

@end

@implementation SENavigationViewController

- (instancetype)initWithRootViewController:(UIViewController *)rootViewController {
    if (self = [super initWithRootViewController:rootViewController]) {
        [self setNavigationBarTheme];
        self.delegate = self;
    }
    return self;
}


// 主题
- (void)setNavigationBarTheme {
    
    // title属性
    UINavigationBar *bar = [UINavigationBar appearance];
    NSDictionary *attr = @{NSForegroundColorAttributeName:[UIColor whiteColor],
                           NSFontAttributeName:FontTitle};
    [bar setTitleTextAttributes:attr];
    
    // 背景颜色
    [bar setBackgroundImage:[UIImage createImageWithColor:HEXCOLORV(ColorMain)] forBarMetrics:UIBarMetricsDefault];
    [bar setShadowImage:[UIImage createImageWithColor:HEXCOLORV(ColorMain)]];
    
    
    // 按钮图片渲染
    [bar setTintColor:[UIColor whiteColor]];
    // 设置返回按钮箭头
    [bar setBackIndicatorImage:[UIImage imageNamed:@"nav_back"]];
    [bar setBackIndicatorTransitionMaskImage:[UIImage imageNamed:@"nav_back"]];
    
    // 按钮属性
    UIBarButtonItem *item = [UIBarButtonItem appearance];
    NSDictionary *itemAttr = @{NSForegroundColorAttributeName:[UIColor whiteColor],NSFontAttributeName:[UIFont systemFontOfSize:16]};
    [item setTitleTextAttributes:itemAttr forState:UIControlStateNormal];
    [item setTintColor:[UIColor whiteColor]];
}

- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated {
    
    // 隐藏tabBar
    if (self.viewControllers.count == 1) {
        viewController.hidesBottomBarWhenPushed = YES;
    }
    
    // 去掉返回按钮文字
    UIBarButtonItem *backitem = [[UIBarButtonItem alloc] initWithTitle:@"" style:UIBarButtonItemStylePlain target:nil action:nil];
    viewController.navigationItem.backBarButtonItem = backitem;
    
    [super pushViewController:viewController animated:animated];
}

- (UIStatusBarStyle)preferredStatusBarStyle {
    return self.visibleViewController.preferredStatusBarStyle;
}


- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
}

@end