iOS11 设置大标题

iOS11 导航栏标题样式 改变了，可以设置大标题了

if (@available(iOS 11.0, *)) {
        self.navigationController.navigationBar.prefersLargeTitles = YES;
        self.navigationController.navigationItem.largeTitleDisplayMode =  UINavigationItemLargeTitleDisplayModeAutomatic;
    } else {
        // Fallback on earlier versions
    }

 largeTitleDisplayMode有三种模式供选择

typedef NS_ENUM(NSInteger, UINavigationItemLargeTitleDisplayMode) {
    /// 自动显示大标题或小标题(初始时是大标题，当滑动使大标题隐藏时显示小标题)
    UINavigationItemLargeTitleDisplayModeAutomatic,
    /// 总是显示大标题
    UINavigationItemLargeTitleDisplayModeAlways,
    /// 总是显示小标题
    UINavigationItemLargeTitleDisplayModeNever,
} NS_SWIFT_NAME(UINavigationItem.LargeTitleDisplayMode);