iOS 7 自定义Back按钮 与 Pop interactive gesture 问题

1、自定义Back按钮

iOS中很多时候我们都会自定义返回按钮，也是一件easy的事，类似如下：

 // 返回按钮
 1 - (void)showNavBackButton
{
    UIButton *backButton = [UIButton buttonWithType:UIButtonTypeCustom];
    [backButton addTarget:self action:@selector(backButtonAction:)
         forControlEvents:UIControlEventTouchUpInside];
    [backButton setBackgroundImage:[UIImage imageNamed:@"00_back_button"]
                          forState:UIControlStateNormal];
    [backButton setTitle:kLoc(@"Back") forState:UIControlStateNormal];
    [backButton setTitleEdgeInsets:UIEdgeInsetsMake(0, 5, 1, 0)];
    backButton.titleLabel.font = kMediumFont(12);
    backButton.frame = CGRectMake(0, 0, 51, 31);
    self.navigationItem.leftBarButtonItem
    = [[UIBarButtonItem alloc] initWithCustomView:backButton];
}

但是，这样在iOS7下Pop interactive gesture就不好使了。

这里 Here 有一个解决方法。

但是，测试发现在栈中推入一个controller后，快速向左平滑，将会引起崩溃。

查看崩溃日志，发现如下信息：

nested pop animation can result in corrupted navigation bar

2、解决Pop interactive gesture问题

优化的解决方案是简单的让NavigationController自己成为响应的接受者，最好用一个UINavigationController的子类。

1)在过渡的时候禁用interactivePopGestureRecognizer

2)当新的视图控制器加载完成后再启用，建议使用UINavigationController的子类操作

 // 自定义NavigationController
 1 @interface DCBaseNavigationController ()
<
UINavigationControllerDelegate,
UIGestureRecognizerDelegate
>
@end

@implementation DCBaseNavigationController

- (void)dealloc
{
    self.interactivePopGestureRecognizer.delegate = nil;
    self.delegate = nil;
    
    [super dealloc];
}

#pragma mark - View lifecycle

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    
    if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
        self.interactivePopGestureRecognizer.delegate = self;
        self.delegate = self;
    }
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

#pragma mark - Override

- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated
{
    // Hijack the push method to disable the gesture
    if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
        self.interactivePopGestureRecognizer.enabled = NO;
    }
    
    [super pushViewController:viewController animated:animated];
}

#pragma mark - UINavigationControllerDelegate

- (void)navigationController:(UINavigationController *)navigationController
       didShowViewController:(UIViewController *)viewController
                    animated:(BOOL)animate
{
    if ([navigationController respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
        navigationController.interactivePopGestureRecognizer.enabled = YES;
    }
}

@end

3、Pop interactive gesture冲突，造成页面假死问题

我遇到的情况是，Push/Pop页面时，没有立即得到想要的效果，页面没有显出出来，NavigationController的didShowViewController:回调方法也没有调用。

页面布局情况是这样的：视图A，有一个Pan手势；视图B是TabBarController，其ViewControllers都是NavigationController。视图B是视图A的子视图。

后来找到原因是：navigationController的interactive pop手势与视图A的pan手势冲突。

具体原因是：rootViewController加载时，调用了didShowViewController:，设置interactivePopGestureRecognizer可用，其实我们并不需要在root的时候也触发这个手势。所以稍加优化如下：

 // 优化
 1 - (void)navigationController:(UINavigationController *)navigationController
       didShowViewController:(UIViewController *)viewController
                    animated:(BOOL)animate
{
    if ([navigationController respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
        //if ([[navigationController.viewControllers firstObject] isEqual:viewController]) {
        if ([navigationController.viewControllers count] == 1) {
            // Disable the interactive pop gesture in the rootViewController of navigationController
            navigationController.interactivePopGestureRecognizer.enabled = NO;
        } else {
            // Enable the interactive pop gesture
            navigationController.interactivePopGestureRecognizer.enabled = YES;
        }
    }
}

当前显示的是root时，设置interactivePopGestureRecognizer不可用，非root时设置interactivePopGestureRecognizer可用。

参考文章：http://keighl.com/post/ios7-interactive-pop-gesture-custom-back-button/