前段时间mac重装系统，所有软件都清除了，下载从商店里面安装Xcode 12.5.1版本，直接提示“要求mac os 11.0或更高版本，于是乎开始升级mac os，检查更新并更新之后，最新版本就是macOS Catalina10.15.7，再也升不上去了，商店里面查看历史版本均找不到下载或获取的入口。折腾一番之后在官网下载了一个11.7版本的xcode。
官方下载地址导航
建议从官方导航里面去寻找需要的工具，需要登录/download/all/?q=xcode
选择下面地址进行下载
下载地址有可能存在官方删除调整导致如下具体的下载地址无效或无法访问，下面仅列出几个Command Line Tools for Xcode 13 beta 2 下载
This package enables UNIX-style development via Terminal by installing command line developer tools, as well as macOS SDK frameworks and headers. Many useful tools are included, such as the Apple LLVM compiler, linker, and Make. If you use Xcode, these tools are also embedded within the Xcode IDE.
Xcode 12.5.1 下载
This is the complete Xcode developer toolset for Apple Watch, Apple TV, iPhone, iPad, and Mac. It includes the Xcode IDE, iOS Simulator, and all required tools and frameworks for building iOS, watchOS, tvOS, and macOS apps.
Command Line Tools for Xcode 12.5.1 下载
This package enables UNIX-style development via Terminal by installing command line developer tools, as well as macOS SDK frameworks and headers. Many useful tools are included, such as the Apple LLVM compiler, linker, and Make. If you use Xcode, these tools are also embedded within the Xcode IDE.
Xcode 12.5 下载
This is the complete Xcode developer toolset for Apple Watch, Apple TV, iPhone, iPad, and Mac. It includes the Xcode IDE, iOS Simulator, and all required tools and frameworks for building iOS, watchOS, tvOS, and macOS apps.
Additional Tools for Xcode 12.5 下载
This package includes audio, graphics, hardware I/O, and other auxiliary tools. These tools include AU Lab, OpenGL Driver Monitor, OpenGL Profiler, Pixie, Quartz Debug, HomeKit Accessory Simulator, IO Registry Explorer, Network Link Conditioner, PacketLogger, Printer Simulator, 64BitConversion, Clipboard Viewer, Crash Reporter Prefs, Dictionary Development Kit, Help Indexer, and Modem Scripts.
Command Line Tools for Xcode 12.5 下载
This package enables UNIX-style development via Terminal by installing command line developer tools, as well as macOS SDK frameworks and headers. Many useful tools are included, such as the Apple LLVM compiler, linker, and Make. If you use Xcode, these tools are also embedded within the Xcode IDE.
Xcode 11.7 下载
This is the complete Xcode developer toolset for Apple Watch, Apple TV, iPhone, iPad, and Mac. It includes the Xcode IDE, iOS Simulator, and all required tools and frameworks for building iOS, watchOS, tvOS and macOS apps.
