网上已经很多适配文章了，这里说一下我们项目遇到、而网文遗漏一些的iOS11、iPhoneX适配问题。

1.缺失 iPhone X 尺寸的启动图，导致应用起来后，顶部和底部有大片黑边。提供一个1125*2436尺寸的启动图即可；

2.导航栏后退按钮样式怪异。下图中前者是iOS11前的效果，后者是iOS11后的。

正常后退按钮效果.png

iOS11回退按钮.png

解决办法：增加ViewController的category并实现以下方法，在进入ViewController 前调用 configureBackBarButtonItemWithNormalImage:hilightedImage:

- (void)configureBackBarButtonItemWithNormalImage:(UIImage *)normalImg hilightedImage:(UIImage *)hlImg
{
    // iOS 11.0 前后导航栏的UI结构发生很大变化，对于返回按钮的实现方式也是不同
    if (@available(iOS 11.0, *)) {
        // iOS 11.0 以后的处理方式
        UIImage *backButtonImage = [normalImg?:hlImg imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
        self.navigationController.navigationBar.backIndicatorImage = backButtonImage;
        self.navigationController.navigationBar.backIndicatorTransitionMaskImage = backButtonImage;

        UIBarButtonItem *returnButtonItem = [[UIBarButtonItem alloc] initWithCustomView:[UIView new]];
        self.navigationItem.backBarButtonItem = returnButtonItem;

    } else {
        // iOS 11.0 前处理方式
        UIBarButtonItem *returnButtonItem = [[UIBarButtonItem alloc]
                                             initWithTitle:@""
                                             style:UIBarButtonItemStylePlain
                                             target:nil
                                             action:nil];
        
        UIImage *realNormalImg = normalImg?:hlImg;
        UIImage *realHighlightedImg = hlImg?:realNormalImg;
        if (realNormalImg) {
            [returnButtonItem setBackButtonBackgroundImage:[realNormalImg resizableImageWithCapInsets:UIEdgeInsetsMake(0, realNormalImg.size.width, 0, 0)]
                                                  forState:UIControlStateNormal
                                                barMetrics:UIBarMetricsDefault];
        }
        
        if (realHighlightedImg) {
            [returnButtonItem setBackButtonBackgroundImage:[realHighlightedImg resizableImageWithCapInsets:UIEdgeInsetsMake(0, realNormalImg.size.width, 0, 0)]
                                                  forState:UIControlStateHighlighted
                                                barMetrics:UIBarMetricsDefault];
        }
        
        [returnButtonItem setBackButtonTitlePositionAdjustment:UIOffsetMake(0, -60) forBarMetrics:UIBarMetricsDefault];
        self.navigationItem.backBarButtonItem = returnButtonItem;
    }
}

3.leftBarButtonItem 距离屏幕左边太宽。

iOS11 leftBarButtonItem 效果.png

这个问题在iOS 11 以下可以通过设置一个负数 space 的 barItem 来缩减间隙。但是iOS 11 以后失效了。对比网上其他人的方法，我使用另一种方法，主要思路是使用 initWithCustomView: 方法，把操作按钮包装成 UIBarButtonItem，设置UIButton 的contentHorizontalAlignment为Left。但但但这个方法有一个问题就是在 iOS11 leftBarItem 距离左边永远存在16pt的大小，即使你可能通过contentInsets可以把图片往左边靠，但实际上他的frame依然没改变，这个16pt的间隙是无法点击的。

- (UIBarButtonItem *)createBackBarButtonItemWithActionBlock:(void(^)(id sender))actionBlock
{
    return [self createLeftBarButtonItemWithIconImage:[[UIImage imageNamed:@"back_gold"] imageByTintColor:[UIColor whiteColor]] itemWidth:30 actionBlock:actionBlock];
}

- (UIBarButtonItem *)createCloseBarButtonItemWithActionBlock:(void(^)(id sender))actionBlock
{
    return [self createLeftBarButtonItemWithIconImage:[[UIImage imageNamed:@"close_gold_no_edge"] imageByTintColor:[UIColor whiteColor]] itemWidth:30 actionBlock:actionBlock];
}

- (UIBarButtonItem *)createLeftBarButtonItemWithIconImage:(UIImage*)iconImage
                                                itemWidth:(CGFloat)itemWidth
                                              actionBlock:(void(^)(id sender))actionBlock
{
    UIView *contentView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, itemWidth, 30)];
    UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
    button.frame = contentView.bounds;
    [button setTitle:nil forState:UIControlStateNormal];
    [button setImage:iconImage forState:UIControlStateNormal];
    [button setContentHorizontalAlignment:UIControlContentHorizontalAlignmentLeft];
    
    if (actionBlock) {
        [button setBlockForControlEvents:UIControlEventTouchUpInside block:actionBlock];
    }
    [contentView addSubview:button];
    
    UIBarButtonItem *barButtonItem = [[UIBarButtonItem alloc] initWithCustomView:contentView];
    return barButtonItem;
}

UIBarButtonItem *closeItem = [self createCloseBarButtonItemWithActionBlock:^(id sender) {
          // TODO something
            }];
UIBarButtonItem *backItem = [self createBackBarButtonItemWithActionBlock:^(id sender) {
                // TODO something
            }];
self.navigationItem.leftBarButtonItems = @[backItem,closeItem];

适配后的效果.png

参考链接：
https://juejin.im/entry/59bf88856fb9a00a5474e394
http://blog.csdn.net/csdnnews/article/details/78127641
http://www.10tiao.com/html/216/201709/2652552758/2.html