iOS15适配

1、处理UINavigationBar默认为透明方法

//OC
if (@available(iOS 13.0, *)) {
    UINavigationBarAppearance * appearance = [[UINavigationBarAppearance alloc] init];
    // 背景色
    appearance.backgroundColor = [UIColor whiteColor];
    // 去除导航栏阴影（如果不设置clear，导航栏底下会有一条阴影线）
    appearance.shadowColor = [UIColor clearColor];
    // 字体颜色、尺寸等
    appearance.titleTextAttributes = @{NSForegroundColorAttributeName: [UIColor redColor]};
    // 带scroll滑动的页面
    self.navigationController.navigationBar.scrollEdgeAppearance = appearance;
    // 常规页面
    self.navigationController.navigationBar.standardAppearance = appearance;
}

//Swift
if #available(iOS 13.0, *) {
    let appearance = UINavigationBarAppearance()
    // 设置导航栏背景色
    appearance.backgroundColor = .white
    // 去除导航栏阴影（如果不设置clear，导航栏底下会有一条阴影线）
    appearance.shadowColor = UIColor.clear
    // 字体颜色、尺寸等
    appearance.titleTextAttributes = [NSAttributedString.Key.foregroundColor: UIColor.white]
    // 带scroll滑动的页面
    navigationController?.navigationBar.scrollEdgeAppearance = appearance
    // 常规页面
    navigationController?.navigationBar.standardAppearance = appearance
}

2、同样的UITabBar也需要用UITabBarAppearance来设置属性：

//OC
if (@available(iOS 13.0, *)) {
    UITabBarAppearance * appearance = [[UITabBarAppearance alloc] init];
     // 背景色
    appearance.backgroundColor = [UIColor whiteColor];
    self.tabBar.standardAppearance = appearance;
    if (@available(iOS 15.0, *)) {
        self.tabBar.scrollEdgeAppearance = appearance;
    }
}

//swift
if #available(iOS 13.0, *) {
    let appearance = UITabBarAppearance()
   // 背景色
    appearance.backgroundColor = .white
    tabBar.standardAppearance = appearance
    if #available(iOS 15.0, *) {
        tabBar.scrollEdgeAppearance = appearance
    }
}

3、UITableView错位问题：

//Swift
if #available(iOS 15.0, *) {
    tableView.sectionHeaderTopPadding = 0
}

//或者appdelegate全局设置
if #available(iOS 15.0, *) {
    UITableView.appearance().sectionHeaderTopPadding = 0
}

//OC
if (@available(iOS 15.0, *)) {
    tableView.sectionHeaderTopPadding = 0;
}

//或者appdelegate全局设置
if (@available(iOS 15.0, *)) {
    [UITableView appearance].sectionHeaderTopPadding = 0;
}