是否可以根据SDK版本隐藏代码

Question

因为我的构建机器仍然使用Xcode12.5，所以UITabBar的scrollEdgeAppearance(它将不存在于Xcode12.5的SDK中)将使构建失败，即使我使用@available进行检查。

if (@available(iOS 15.0, *)) {
    UINavigationBarAppearance* navBarAppearance = [UINavigationBarAppearance new];
    navBarAppearance.backgroundColor = [UIColor colorNamed:@"navbar_bg"];

    [UINavigationBar appearance].standardAppearance = navBarAppearance;
    [UINavigationBar appearance].scrollEdgeAppearance = navBarAppearance;
    
    UITabBarAppearance* tabBarAppearance = [UITabBarAppearance new];
    tabBarAppearance.backgroundColor = [UIColor colorNamed:@"second_bg"];
    [UITabBar appearance].standardAppearance = tabBarAppearance;
    [UITabBar appearance].scrollEdgeAppearance = tabBarAppearance;
    
    [UITableView appearance].sectionHeaderTopPadding = 0;
}

所以有没有可能做这种SDK签入代码，当构建SDK不是最新的SDK时，这些代码将不会参与构建？像这样

if (BuilDSDK >= someversion) 
{
   [UITabBar appearance].scrollEdgeAppearance = tabBarAppearance;
}

Answer 1

@available是一种运行时可用性检查，在这种情况下不能真正用于编译时的内容。

在Objective-C中，您可以将iOS 15SDK上应用的代码部分封装到另一个宏条件中：

#ifdef __IPHONE_15_0
    if (@available(iOS 15.0, *)) {
        ...
    } else {
#endif
        // possible legacy branch code
#ifdef __IPHONE_15_0
    }
#endif

__IPHONE_15_0是从iOS 15 SDK开始定义的，因此在Xcode12/iOS 14 SDK中构建时会被省略。?

Answer 2

Swift类的另一个类似的解决方案可以在这里找到：https://stackoverflow.com/a/69583441/1195661

#if swift(>=5.5) // Only run on Xcode version >= 13 (Swift 5.5 was shipped first with Xcode 13).
        if #available(iOS 15.0, *) {
            UITabBar.appearance().scrollEdgeAppearance = tabBarAppearance
        }
#endif